Landscape Message: May 5, 2023

UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Massachusetts Green Industry professionals in the management of our collective landscape. Detailed reports from scouts and Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. The following issue has been updated to provide timely management information and the latest regional news and environmental data.

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Scouting Information by Region

Environmental Data

The following data was collected on or about May 3, 2023. Total accumulated growing degree days (GDD) represent the heating units above a 50ºF baseline temperature collected via regional NEWA stations (http://newa.cornell.edu) for the 2023 calendar year. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

MA Region/Location	GDD		Soil Temp (°F at 4" depth)		Precipitation (Gain since last report)	Time/Date of Readings
	(Gain since last report)	2023 Total	Sun	Shade
CAPE	15	95	54	51	2.28	12:00 PM 5/3/23
SOUTHEAST	19	110	60	52	3.35	3:00 PM 5/3/23
NORTH SHORE	5	67	51	47	4.07	10:00 AM 8/3/23
EAST	16	105	52	49	2.53	4:00 PM 5/3/23
METRO	8	87	47	46	2.54	6:45 AM 5/3/23
CENTRAL	8	99	51	48	4.29	7:00 AM 5/3/23
PIONEER VALLEY	20	102	55	50	6.36	12:00 PM 5/3/23
BERKSHIRES	10	93	50F	48F	3.31	5:45 AM 5/3/23

Phenology

Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END)
PLANT	CAPE	SE	NS	EAST	METRO	CENT	PV	BERK
Spiraea x vanhouttei (Vanhoutte spirea)	*	*	*	*	Begin	Begin	Begin	*
Elaeagnus umbellata (autumn olive)	*	Begin	Begin	*	Begin	Begin	Begin	*
Syringa vulgaris (common lilac)	Begin	Begin	Begin	Begin	Begin	Begin	Begin	Begin
Cornus florida (flowering dogwood)	Begin	Begin	Begin/Full	Begin/Full	Begin/Full	Begin/Full	Full	Begin
Rhododendron spp.(early azaleas)	Begin	Begin	Begin	Begin	*	*	Begin	Begin
Malus spp. (crabapple)	Begin	Full	Full	Full	Full	Full	Full	Begin/Full
Cercis canadensis (redbud)	Begin/Full	Full	Begin/Full	Begin/Full	Full	Full	Full	Full
Rhododendron 'P.J.M.'	End	Full/end	Full/End	Full/End	Full/end	Full/End	Full/End	Begin/Full
Amelanchier spp. (shadbush, serviceberry)	Full/End	End	End	End	End	End	End	Full
Magnolia soulangeana (saucer magnolia)	End	End	End	End	End	End	End	Full/End
Pyrus calleryana (Callery pear)	End	End	End	End	End	End	End	Full
Rhododendron mucronulatum (Korean rhododendron)	*	End	*	End	End	Full/End	Full/End	Full/End

Regional Notes

Cape Cod Region (Barnstable)

General Conditions: The average temperature for the period from April 19th to May 3rd was 49°F, with a high of 62°F on May 2nd and a low of 35°F on April 27th. Conditions were much cooler than the previous period. The period had a fairly even amount of sunny, partially sunny, and cloudy days. Precipitation occurred on April 23th, 29th, 30th and May 1st, providing 2.25 inches and keeping soil moisture adequate. 

Some herbaceous plants seen in bloom include tulips, grape hyacinth (Muscari armeniacum), lungwort (Pulmonaria officinalis), barrenwort (Epimedium spp.), fringed bleeding heart (Dicentra eximia), and solomon’s seal (Polygonatum odoratum). Woody plants seen bloom include forsythia (Forsythia spp.), flowering quince (Chaenomeles speciosa), Japanese cherry (Prunus serrulata ‘Kwanzan’), koreanspice viburnum (Viburnum carlesii), and blueberry (Vaccinium corymbosum). Oaks in the red oak group have begun to flower.  

Pests/Problems: Winter injuries in the landscape are still the primary issue. Damage to buds and woody tissues are abundant on bigleaf hydrangea (H. macrophylla) and butterfly bush (Buddleia davidii). These plants can be cut to the ground to focus on new shoots from the base.  Other winter injuries are primarily on needled and broadleaved evergreens. Winter moth caterpillars are feeding and are fairly easy to find on maples and rosaceous plants. Treatment for winter moth is generally not warranted as the insect has been controlled by biocontrols in recent years. 

Other problems observed during the period include reversion of Alberta spruce (Picea glauca ‘Conica’), drought injury on rhododendron and arborvitae, and interior/lower limb browning on Leyland cypress (shading). 

Weeds in bloom include garlic mustard (Alliaria petiolate), dandelion (Taraxacum officinale), corn speedwell (Veronica arvensis), deadnettle (Lamium purpureum), and common violet (Viola papilionacea), yellow rocket (Barbarea vulgaris) and cypress spurge (Euphorbia cyparissias).

Lawns are being mowed. Rabbits are feeding on perennials. Keep yourself protected from ticks.

Southeast Region (Dighton)

General Conditions: The weather has been quite seasonable over the past two weeks. Thankfully we seem to have shifted to a pattern of regular showers and rainfall, for now at least. The highest daytime temperature was 56°F on April 26th. The overnight low was 35°F on May 3rd. We've had partial showers, or rain, every day since April 30th. The peak wind gust was 25 mph also on April 30th.

Plants in flower: Alliaria petiolata (garlic mustard), Aquilegia (columbine), Cercis canadensis (eastern redbud), Chaenomeles (flowering quince), Convallaria majalis (lily-of-the-valley), Cornus florida (native flowering dogwood), Deutzia, Elaeagnus umbellata (autumn olive), Fothergilla (witch alder), Fragaria × ananassa (strawberry), Geranium maculatum (spotted cranesbill), Halesia carolina (silverbell), Lonicera (invasive bush honeysuckles), Lunaria annua (honesty, money plant), Magnolia × soulangeana (saucer magnolia), Malus (apples), Narcissus (daffodils), Polygonatum biflorum (great Solomon's seal), Prunus (cherries), P. maritimus (beach plum), P. pumilus (sand cherry), P. serrulata 'Kanzan' (Kanzan flowering cherry), Phlox stolonifera (creeping phlox), Pyrus (pears), Quercus (oaks), Rhododendron mucronulatum (Korean azalea), R. vaseyi (pinkshell azalea), R. (PJM group), Syringa vulgaris (lilac), Tulipia (tulips), Vaccinium corymbosum (highbush blueberry), Viburnum carlesii (Korean spice viburnum), Vinca minor (myrtle)

Pests/Problems: Crabgrass has begun to germinate. Seedlings are now at the two and three-leaf stages. Eastern tent caterpillar webbing is approximately six inches in diameter on native black cherry. Hedge bindweed vines are approximately six to ten inches long. European pine sawfly larvae are approximately ½ inch long. 

North Shore (Beverly)

General Conditions: During this two-week reporting period, we had cloudy and rainy weather with cooler than normal spring temperatures most days. Day temperatures were in the low to mid-50s with night temperatures in the low to mid-40s. The average daily temperature was 48˚F, with a minimum temperature of 35˚F recorded on April 28, and a high of 62˚F on May 1. Rainfall was recorded on several days with most recorded after two major storms on April 23rd and 30th. A total of 4.07 inches of rainfall were recorded at Long Hill during this period. Soils are very moist and not suitable for working. Wait for conditions to dry out before working soil. Woody plants observed in bloom or starting to bloom include: mountain Pieris (Pieris floribunda), flowering dogwood (Cornus florida), redbud (Cercis canadensis), large Fothergilla (Fothergilla major), Daphne (Daphne sp.), common lilac (Syringa vulgaris), crabapple (Malus spp.) and Burkwood Viburnum (Viburnum x burkwoodii). Non-woody plants seen in bloom include: daffodil (Narcissus spp.), forget-me-not (Myosotis sylvatica), tulips (Tulipa spp.), bleeding heart (Dicentra spectabilis), vinca vine (Vinca minor) and Trillium (Trillium grandiflorum).

Pests/Problems: Weeds seen in bloom include: dandelion (Taraxacum officinale), lesser celandine (Ranunculus ficaria), ground ivy (Glechoma hederacea), common blue violet (Viola papilonacea) and purple deadnettle (Lamium purpureum). No insect pest activity was reported. However, remember that ticks are active. Protect yourself with repellent when working outdoors.

East Region (Boston)

General Conditions: It has been unusually cool for late April. Over the past two weeks daytime temperatures averaged 56°F with overnight lows averaging 44°F. We had precipitation on eight of the past 14 days including two significant rain events. On April 23 we received .76 inches and on April 30 we received .91 inches, for a total of 2.53 inches of beneficial precipitation. The landscape is slowly greening up. Plants observed in bloom include: Cercis canadensis (redbud), Cornus florida (flowering dogwood), Malus spp. (crabapple), Prunus maritima (beach plum), Syringa vulgaris (common lilac), Vaccinium corymbosum (high bush blueberry) and Viburnum carlesii (Korean spice Viburnum).

Pests/Problems: Winter moth caterpillars (Opterophtera brumata) are feeding on emerging leaves of maple (Acer spp.), apple (Malus spp.) and rose (Rosa spp.). Many plants continue to show signs of winter/spring injury. Hydrangea macrophylla (big leaf Hydrangea) are flushing out from the base with little to no top growth. Mature plantings of sweet autumn clematis (Clematis terniflora),  lavender (Lavendula spp.) and knockout roses (Rosa spp.) are all suffering from top dieback. Garlic mustard (Arrilaria petiolata) is flowering. Japanese knotweed (Polygonum cuspidatum) is thriving along roadsides.

Metro West (Acton)

General Conditions: Happy belated Arbor Day! This year marks its 151st anniversary, a holiday dedicated to planting and caring for trees. It sure feels like spring with the mix of cool and warm temperatures and windy and rainy weather that we have been experiencing over the past two weeks. A high temperature of 66°F was recorded on the 20th with a low of 36°F on the 28th. The average rainfall total for the month of April is 4.15” and I recorded a total of 2.21”, accumulating 1.78” during this reporting period. According to NOAA, the 20-year average rainfall total for the month of May is 3.37”. The total precipitation that I have recorded for the month so far is 7.56”. Some amount of precipitation was recorded on all but four days these past two weeks.

Pests/Problems: Alliaria petiolata (Garlic Mustard) continues to thrive, grow, and flourish everywhere in the landscape. It is just beginning to flower and can easily be seen because of its white flowers. Other spontaneous flowering plants seen in bloom are: Draba verna (spring whitlow grass), Glechoma hederacea (ground ivy) and Lamium purpureum (purple deadnettle), Stellaria media (common chickweed), and Taraxacum officinale (dandelion). Other spontaneous plants emerging but not yet in bloom include: Arctium minus (lesser burdock), Impatiens capensis (touch-me-not) and Polygonum cuspidatum (Japanese knotweed). Be aware of Toxicodendron radicans (Poison Ivy). It is beginning to leaf out, so it is easy to detect its shiny red leaves of three.

Central Region (Boylston)

General Conditions: The weather this reporting period was typical for late April - a mix of clouds and sun, periods of rain, heavy at times, and temperatures fluctuating between low-40’s overnight and mid-60’s during the day. We received more than four inches of rain, in stark contrast to earlier this growing season and last year when we were in the early stages of a substantial drought by this time. There is plenty in bloom throughout the region, including many native spring ephemerals. Trillium grandiflorum (white wakerobin), Stylophorum diphyllum (wood poppy), and Mertensia virginica (Virginia bluebells) all are at or near peak bloom, brightening many a woodland garden. Daffodils have largely petered out, but tulips are now in full swing. Many ferns have unfurled their first fronds - Polystichum acrostichoides (Christmas fern) is well past the fiddlehead stage and the Matteuccia struthiopteris (fiddlehead fern) fronds are already a foot or taller. All the rain has made the landscape lush, green, and colorful.

Pests/Problems: Lawn weeds are going strong. Dandelion (Taraxacum officinale), creeping Charlie (Glechoma hederacea), and purple deadnettle (Lamium purpureum) all are quite active and flowering. Marginally hardy plants like sweetbox (Sarcococca hookeriana) are showing significant winter dieback from the -15°F temperatures we experienced in early February. Poison ivy (Toxicodendron radicans) has begun active growth. Second year garlic mustard (Alliaria petiolata) is in full bloom.

Pioneer Valley (Amherst)

General Conditions: After a warm, sunny and dry start to April, the second half of the month was cool and cloudy with bountiful precipitation. Two significant storms occurred on 4/22–23 (3.96″) and 4/30–5/1 (1.52″), while several other scattered storms delivered additional rainfall. Once again, soils are wet to saturated this spring season. The big warmup from 4/10–4/16 propelled flowering and new growth on perennials and woody plants, but since then it’s been a slow burn. The return to seasonable temperatures has restrained development and growth is now occurring at a measured rate. Low temperatures dropped below freezing in the valley bottom on 4/25 and 4/26. Despite a proliferation of tender shoots and foliage, damage was very isolated. Hopefully, this was the last frost of the spring season. Conditions have generally been good for new plantings. For many woody plants, a considerable amount of new root production occurs before June and the cool, moist soils lessen the shock of transplant. The early April heat hastened magnolia flowering, but redbuds have enjoyed an especially prolonged period of full flower. Of all the spring flowering trees, redbud is arguably the most unique in color. Crabapples and apples are now in full bloom and should remain so with the mild temperatures in the long-term forecast. When the flowers encircle the branches, creating a spire of blooms protruding from the canopy, these small trees are stunning. This was not a great year for flowering cherries. As discussed previously, Weeping Higan and Sargent cherries throughout Hampshire County barely flowered. Many are now pushing new growth, but only slowly and with many leafless shoots. The spring is always a good time to remind clients that planting trees directly into turfgrass is undesirable. From Vertrees & Gregory (2009; p. 45)¹: "A newly planted Japanese maple needs several years before its relatively shallow root system is established enough to successfully compete with other vegetation for moisture and nutrients. The competition from grass is especially intense. Hence, the area around a newly planted maple should be kept weed-free for the first two to three years." Turfgrasses are lush right now and growing strong with the regular rainfall and cool temperatures. Also discussed previously, broken branches on trees and shrubs from heavy snow in December and March is a common sight throughout the valley and hill towns. The affected branches should be pruned out or tied upright (in the case of yew and arborvitae). Peepers and tree frogs continue to be active while the cool temperatures have suppressed black flies and mosquitoes.  

¹Vertrees J.D. and Gregory P. 2009. Japanese Maples: The Complete Guide to Selection and Cultivation (4th edn.). Timber Press, Portland, OR. 404 p.  

Pests/Problems: Pest and pathogen activity are slowly taking shape as the spring season progresses. Beech are leafing out and symptoms of beech leaf disease should be readily visible soon. Look for dark green, interveinal banding, distortion and cupping of the foliage. The concurrence of regular rainfall from 4/23 through 5/3 (time of writing) and new leaf development on apple and crabapple has created excellent conditions for apple scab (Venturia inaequalis) infections. Good early season conditions for disease development can spur a big year for this common pathogen. The late April rain also spurred prolific spore production for certain Gymnosporangium species. A mass planting of eastern red-cedar (Juniperus virginiana) on the UMass campus were inundated with orange-colored spore masses from G. clavipes (cedar-quince rust) and G. juniperi-virginianae (cedar-apple rust) (see figure below). The trees were planted in a location with only half-sun and are close to several hawthorns and crabapples (alternate hosts). Junipers and red-cedar should only occupy sites with full sun to help minimize rust diseases. Some early season leaf rolling and defoliation has been observed but identifying a culprit is often challenging. With new growth appearing on eastern hemlock and true fir, we are entering a preferred time period for control of hemlock wooly adelgid (hemlock only) and elongate hemlock scale (hemlock and fir) using dinotefuran. A single application to the lower trunk can provide two and possibly even three years of protection against these destructive insect pests. Lacebug (Stephanitis) injury on Japanese andromeda (Pieris japonica) is widespread right now (see figure). Lacebugs thrive during periods of drought and populations were high in 2022. Infested plants can be treated with spinosad after plants bloom to avoid any contact with pollinators. The underside of the foliage must be coated, so application can be a bit challenging. Avoid the use of imidacloprid or dinotefuran as these chemicals may be present in next year’s pollen. Winter injury on boxwood is abundant this spring season. Oriental bittersweet seedlings are emerging and every effort should be made to remove these before they establish.

Berkshire Region (West Stockbridge)

General conditions: After some unseasonable warmth, temperatures over the past two weeks have, for the most part, been below normal. There was one warm day, April 21st, when temperatures were well above normal: 74°F in Richmond and Pittsfield, and 76°F in North Adams. In most parts of the county, frost occurred on three days during this same period with the lowest temperatures occurring on April 26th: 27°F in Richmond and 29°F in Pittsfield and North Adams. The normal high temperature at this point in time at the Pittsfield Airport is 63°F and normal low is 42°F.  While the low temperature has been close to that norm, the daily high temperatures have been typically well below the normal high. Not only has it been cool, but it has also been wet since April 29th. Currently, soils are at or near saturation. Some of this rain is welcomed, given the very dry conditions of late winter and early spring. It does benefit any specimens planted this spring. The early jump that flowering trees and shrubs got on the season due to the warmth of March and April has slowed just a bit. However, natural and managed landscapes are currently flush with bloom. Turfgrass is growing rapidly.

Pests/Problems: Pest pressures remain low. Pests observed at this time include spongy moth caterpillars which appear quite lethargic. Boxwood leaf miner remains in the larval stage, tucked into the blister-like structures on boxwood leaves. Hydrangea leaf tier caterpillars are creating their envelope-like structures by cementing together leaves at the tips of hydrangea branches. Cutworms are commonly observed when working garden soils. Here in West Stockbridge, a common sight is damage to white ash trees relating to infestation by emerald ash borers.  Though not considered a plant pest, I received photos of March flies gathering on a container-grown plant that was infested by aphids. According to information provided by UMass Extension Entomologist, Tawny Simisky, the flies do not feed on aphids (For more information on March flies, see the Insect portion of this week’s Landscape Message). Insect observations at this time also include some beneficials, namely assassin bugs and ground beetles. Weed growth is progressing steadily. The pervasive garlic mustard is currently nearing the flowering stage. Rodent damage to bulbs and plant roots, especially by voles, has been common of late.

Regional Scouting Credits

• CAPE COD REGION - Russell Norton, Horticulture and Agriculture Educator with Cape Cod Cooperative Extension, reporting from Barnstable.
• SOUTHEAST REGION - Brian McMahon, Arborist, reporting from the Dighton area.
• NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
• EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists reporting from the Boston area.
• METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
• CENTRAL REGION - Mark Richardson, Director of Horticulture reporting from New England Botanic Garden at Tower Hill, Boylston.
• PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from Amherst.
• BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.

Woody Ornamentals

Diseases

Recent pests and pathogens of interest seen in the UMass Extension Plant Diagnostic Lab, a select few:

The UMass Plant Diagnostic Lab continues to receive samples of arborvitae (Thuja occidentalis and T. plicata × standishii) suffering from needle blight. In nearly every case, these trees have been weakened and predisposed by other stresses. Examples include drought, winter injury, leafminer, spider mites, transplant shock, restricted rooting zones, excessive heat (radiative and conductive) from nearby hardscapes. With so many arborvitae in the landscape, it’s likely that many are also suffering the long-term effects of poor planting practices. When the roots are left tangled and encircled from the pot at the time of planting, it can take many years for this injury (circling and girdling roots) to manifest in above-ground symptoms. Once weakened, the fungal pathogens Phyllosticta and Pestalotiopsis can readily spread through the canopy to cause further dieback. On otherwise healthy trees, these fungi are rarely a problem. 

Orange-colored slime colonization from pruning wounds on a Japanese snowbell (Styrax japonicus). The slime is likely a combination of fungi and yeasts with one in particular (Fusicola) responsible for the orange coloration. These organisms are utilizing sugars in the sap as it flows from the wounds and appears similar to wetwood bacteria. While aesthetically unpleasing, the slime should have no lasting impact on the wound healing process or health of the tree. In addition to snowbell, the slime can be regularly found on dogwoods (Cornus) too.  

Diplodia shoot blight (Diplodia sapinea) on a Serbian spruce (Picea omorika). The tree is approximately 15- to 20-years-old and was transplanted to the site only nine months ago. It resides in a full sun setting with hand-watering and loam-based soils. This spring, shoot tip dieback with prematurely shedding needles developed. Transplant shock likely predisposed the tree to infection by Diplodia, which can attack spruce when trees are badly weakened. As a needle blight and stem cankering pathogen of conifers (and some hardwoods), D. sapinea is capable of contributing to decline and death if not addressed.

Interior needle browning on an upright, dwarf cultivar of Norway spruce (Picea abies ‘Suncrest Pyramid’). Upon microscopic evaluation, the primary issue appeared to be a serious infestation of the spruce spider mite (Oligonychus ununguis). Additional insect pests present included the spruce bud scale (Physokermes piceae) and cryptomeria scale (Aspidiotus cryptomeriae) (minor infestations). There was also secondary needle blight activity by Lophodermium piceae and Pestalotiopsis. The tree is roughly 15-years-old and was transplanted to the site two years ago. It resides in a part-sun setting with sandy-clay soils with no supplemental irrigation. Drought stress also likely played some role in the dieback. While Norway spruce can handle partial shade, full sun is preferable for robust growth.  

Winter injury of tulips (from Angie Madeiras, UMass Extension Plant Pathologist) has been observed this spring. Symptoms include stunted plants and deformed leaves and/or flowers. Injury is often observed in plantings on sunny, south facing slopes, or in areas where bulbs are not planted deeply enough. To help tulips recover from winter injury, cut the flower stems back as soon as blooms are finished. Do not cut back foliage while any part of it remains green, as the bulbs will need the carbohydrates generated by photosynthesis. Ensure that bulbs are planted at the proper depth, which will protect them against temperature extremes that can influence conditions in the top few inches of the soil. Large bulbs (circumference over 4.75 inches) can be planted 6-8 inches deep and smaller bulbs (circumference under 4.75 inches) can be planted 3-4 inches deep. Alternatively, bulbs may be planted more shallowly and covered with 2-3 inches of mature compost or mulch. Avoid planting too deep, which can result in reduced vigor and fewer blooms next year. Discard bulbs that are less than 2.5 inches in circumference, as they are unlikely to set flowers.

Report by Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass Amherst.

Insects and Other Arthropods

Interesting Insects and Other Odd Animals Reported Recently:

For more information, visit the “Hammerhead Worms in New England” article found in Hort Notes, here: https://ag.umass.edu/landscape/newsletters/hort-notes/hort-notes-2021-vol-3210 .

• Hammerhead Worms: Also known as flatworms or land planarians, belong to Phylum Platyheminthes (flat worms) rather than Arthropoda (arthropods) which makes them different from insects and their relatives. Class Insecta is the taxonomic classification of the Insects, whereas hammerhead worms belong to Class Turbellaria. A few common species of hammerhead worms noted from New England include but are not limited to: Bipalium kewense, Bipalium adventitium, and Bipalium pensylvanicum. Sightings of these organisms have increased in recent years, possibly due to warming winters and wet summers. Hammerhead worms are predators that prefer to feed on earthworms, however depending upon the species involved, they may not be an effective predator of certain species of jumping worms.

Recently, reports of hammerhead worms have come from parts of Massachusetts (Bristol County) with questions about safety. Hammerhead worms are known to produce a neurotoxin (tetrodotoxin) which they use in self-defense and to subdue prey. Luckily, hammerhead worms do not produce enough tetrodotoxin to be lethal to humans, but if the neurotoxin comes into contact with exposed skin, irritation may occur. It is advised that handling hammerhead worms should be avoided, and hands or exposed skin be washed with soap and water following any accidental contact.

• March Flies: are Dipterans in the Family Bibionidae. The common name is confusing, as the adult flies are typically present in April and May. March flies were recently reported in the Berkshire Region Report. See above for details. These flies are found throughout North America and develop in decaying organic matter. Swarms of adults may be startling when found around ornamental plants or blooms. Adult females eventually lay 200-300 eggs in the soil. Eggs hatch and the larvae feed on leaf litter and sometimes between the roots of plants. While March flies may be noticeable and a nuisance to some, they are not typically thought of as pests. They do not cause harm to the health of plants, animals, or humans. For more information, visit: https://content.ces.ncsu.edu/march-flies .
• Thick Headed Flies: true flies (Dipterans) in the Family Conopidae are known as the “thick headed flies”. This Family is “new” to this entomologist, and I extend a thank you to Dr. Jennifer Forman Orth with the MA Department of Agricultural Resources who opened my eyes to the difference between bee and wasp mimicking species in the Conopidae vs. the Syrphidae (hoverflies). Not only do adult thick headed flies have a noticeably broad head, they also possess a long, slender, stiff proboscis (mouthpart) that is bent and extends forward. An arrow points to the proboscis in the photo provided by Bruce Allen on 5/1/2023 from Barnstable County, MA. The halteres (modified hind wings that function like gyroscopes) are also circled in this photo, a first clue that while this thread-waisted insect may look like a wasp, it is a true fly (Diptera) with only 1 pair of membranous wings. Adult thick headed flies may feed on nectar, while the immatures are internal parasites of certain wasps, bees, ants, crickets, cockroaches, and certain other true fly species.

Woody ornamental insect and non-insect arthropod pests to consider, a selected few:

• Deer Tick/Blacklegged Tick: Ixodes scapularis adults are active all winter and spring, as they typically are from October through May, and “quest” or search for hosts at any point when daytime temperatures are above freezing. Engorged females survive the winter and will lay 1,500+ eggs in the forest leaf litter beginning around Memorial Day (late May). For images of all deer tick life stages, along with an outline of the diseases they carry, visit: https://web.uri.edu/tickencounter/species/blacklegged-tick/ .

Anyone working in the yard and garden should be aware that there is the potential to encounter deer ticks. The deer tick or blacklegged tick can transmit Lyme disease, human babesiosis, human anaplasmosis, and other diseases. Preventative activities, such as daily tick checks, wearing appropriate clothing, and permethrin treatments for clothing (according to label instructions) can aid in reducing the risk that a tick will become attached to your body. If a tick cannot attach and feed, it will not transmit disease. For more information about personal protective measures, visit: https://web.uri.edu/tickencounter/prevention/protect-yourself/ . 

The Center for Agriculture, Food, and the Environment provides a list of potential tick identification and testing resources here: https://ag.umass.edu/resources/tick-testing-resources.

In the news: UMass Amherst has now been designated as the location for the New England Center of Excellence in Vector-Borne Diseases (NEWVEC). This CDC (Centers for Disease Control and Prevention) funded center will work to reduce the risk of vector-borne diseases spread by ticks, mosquitoes, and other blood-sucking insects or insect relatives in New England: https://www.umass.edu/news/article/cdc-designates-new-england-center-excellence-vector-borne-diseases-umass-amherst . For more information and to contact NEWVEC, visit: https://www.newvec.org . To contact the center for more information about their Spring 2023 Project ITCH (“Is Tick Control Helping”), visit: https://www.newvec.org/itch .

Note: Dog ticks (Dermacentor variabilis) have recently become noticeably active in parts of Berkshire and Hampshire County in 2023.

Highlighted Invasive Insects & Other Organisms Update:

• Spongy Moth: Lymantria dispar egg masses are laid by the adult female moth on any flat surface, including host plants such as oak, but also fencing, buildings, steps, outdoor furniture, and more. Spongy moth egg masses have begun to hatch, right “on time”, in Berkshire County! Egg hatch typically occurs between 90-100 growing degree days (roughly the first week in May, but this varies depending upon location; in warm springs egg hatch can occur in April).

  Spongy moth egg hatch was reported on April 18, 2023, in Great Barrington, MA (Berkshire County). The tiny caterpillars can be seen on top of the egg mass from which they hatched in the photo courtesy of Tom Ingersoll. Spongy moth egg hatch has also been reported from Erving, MA and Millers Falls, MA (Franklin County) on 5/2/2023. Tiny caterpillars were observed to be dispersing and settling on host plant leaves and beginning to feed. See photos courtesy of Nicole Keleher, MA Department of Conservation and Recreation, Forest Health Program.

Spongy moth caterpillars may again be noticeable in parts of Berkshire County and abutting locations in NY and CT this year, as well as parts of Franklin County that were impacted in 2022. This is despite seeing caterpillar die-off from the spongy moth killing fungus Entomophaga maimaiga last season.

For more information from the MA Department of Conservation and Recreation, Forest Health Program, visit: https://storymaps.arcgis.com/stories/b60f63199fa14805a8b9f7c82447a25b and look under the spongy moth navigation tab.

If large numbers of egg masses are seen, plan to monitor them between 90-100 growing degree days (roughly the first week in May, but this varies) to better time egg hatch and caterpillar emergence. The MA Department of Conservation and Recreation, Forest Health Program reports that winter counts of spongy moth egg masses are higher than hoped for in parts of Berkshire County coming into the spring of 2023. This may mean that spongy moth caterpillars will again be noticeable in these areas this year, despite seeing caterpillar die-off from the spongy moth killing fungus Entomophaga maimaiga last season. For more information from the Forest Health Program, visit: https://storymaps.arcgis.com/stories/b60f63199fa14805a8b9f7c82447a25b and look under the spongy moth navigation tab.

If egg masses are plentiful near high-value specimen trees in Berkshire County in 2023, consider applying the reduced risk insecticide Bacillus thuringiensis Kurstaki (Btk) to host plant leaves before caterpillars are over ¾ inch in length. Work with a licensed pesticide applicator and arborist to plan these applications, if necessary, especially if a high-value host plant was defoliated by this insect in 2021 or 2022.

Additionally, we’ve been asked about wrapping trees to prevent spongy moth caterpillars from accessing the canopy to feed. Here is some information. If you are interested in wrapping trees or shrubs with a sticky barrier to capture older, crawling spongy moth caterpillars, there are a few things to consider. 1) This will not prevent all caterpillars from accessing the tree to feed, nor is it a guarantee that no foliage will be eaten by them on the plant to which it has been applied. 2) This will not prevent the tiniest of caterpillars (newly hatched) from ballooning on the wind into tall trees and settling to feed. For example, this could mean that caterpillars will still have some access to the leaves following their dispersal in the spring. 3) Do not apply any sticky substances directly to the tree or shrub bark to avoid risk of injury to the plant. 4) Sticky bands will need to be monitored frequently throughout the growing season, particularly in mid-to-late May and especially June, to clean and replace them.

If the bands become covered in dead caterpillars, living ones can crawl over the dead and still access the leaves of the tree. You do not have to hang the bands up now, but now is a good time to purchase necessary materials if you are interested in doing this on a few trees or shrubs in your yard. It is recommended that bands be placed on trees (and sticky material on the bands) once the caterpillars are approximately an inch in length. This may be approximately in early or mid-June. Bands should then be left up and changed frequently through July, until the caterpillars have pupated. This technique may work best with an engaged property owner that is willing and able to frequently check and help change the bands. For more information, visit: https://www.canr.msu.edu/resources/using-bands-to-protect-shade-trees-from-spongy-moth

The good news – homeowners in central and eastern Massachusetts will hopefully not have to worry too much about spongy moth this year. It may be undetectable in many central and eastern MA locations. MA DCR reports not seeing significant overwintering spongy moth egg masses in those locations. The primary area of concern includes parts of southwestern Berkshire County.

For more information about spongy moth, view the first episode of InsectXaminer, here: https://ag.umass.edu/landscape/education-events/insectxaminer .

Why did the common name for Lymantria dispar change recently? More information is available here: https://entsoc.org/news/press-releases/spongy-moth-approved-new-common-name-lymantria-dispar .

• Hemlock Woolly Adelgid: Adelges tsugae is present on eastern and Carolina hemlock. The overwintering hemlock woolly adelgid generation (sistens) is present through mid-spring and produces the spring generation (progrediens) which will be present from early spring through mid-summer. HWA, unlike many other insects, does most of its feeding over the winter. Hemlock woolly adelgid winter mortality (due to two significant regional cold snap events) is expected to be high for 2023. HWA that were most likely to survive these extreme cold events are those on lower host tree branches, if they were insulated by snow pack at the time. Determine if HWA are alive or dead on host plants before making chemical management decisions. This can be done quickly in the field by squishing overwintered HWA in their ovisacs between your thumb and forefinger and looking for a dark brown/blackish stain (from the hemolymph, or insect blood). If staining does not occur, the insect may have died and dried up. Test at least a few insects on at least a few branches to determine if any are alive. (Much more extensive examination may involve viewing at least 200 adelgids per site/location to calculate percent winter mortality.)

Eggs may be found in woolly masses at the base of hemlock needles beginning in mid-March. Each woolly mass is created by a female who may then lay 50-300 eggs. Eggs hatch and crawlers may be found from mid-March through mid-July. Infested trees may be treated with foliar sprays in late April to early May, using Japanese quince as a phenological indicator. Systemic* applications may be made in the spring and fall, or when soil conditions are favorable for translocation to foliage. Nitrogen fertilizer applications may make hemlock woolly adelgid infestations worse.

For more information, visit: https://ag.umass.edu/landscape/fact-sheets/hemlock-woolly-adelgid .

*Note: beginning July 1, 2022 systemic insecticides known as neonicotinoids (including imidacloprid) have become state restricted use for tree and shrub uses in Massachusetts. More information is available, here:https://www.mass.gov/service-details/pesticide-newsupdates

• Spotted Lanternfly: (Lycorma delicatula, SLF) is a non-native, invasive insect that feeds on over 103 species of plants, including many trees and shrubs that are important in our landscapes. It overwinters as an egg mass, which the adult female insect lays on just about any flat surface. Pictures of egg masses can be seen here:https://massnrc.org/pests/linkeddocuments/SLFChecklistForResidents.pdf

  States south of Massachusetts (Virginia to Pennsylvania) have begun reporting spotted lanternfly egg hatch for 2023. The MA Department of Agricultural Resources expects that spotted lanternfly eggs should begin hatching in Massachusetts over the course of May. For further updates from MDAR, visit: https://massnrc.org/pests/blog/?p=3187 .

  Currently, the only established populations of spotted lanternfly in Massachusetts are in Fitchburg, Shrewsbury, Worcester, and Springfield MA. Therefore, there is no reason to be preemptively treating for this insect in other areas of Massachusetts. If you suspect you have found spotted lanternfly in additional locations, please report it immediately to MDAR here: https://massnrc.org/pests/slfreport.aspx . If you are living and working in the Fitchburg, Shrewsbury, Worcester, and Springfield, MA areas, please be vigilant and continue to report anything suspicious.

For More Information:

From UMass Extension:

*New*: Spotted Lanternfly Management Guide for Professionals:https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly-management

*Note that management may only be necessary in areas where this insect has become established in Massachusetts, and if high value host plants are at risk. Preemptive management of the spotted lanternfly is not recommended.

Fact Sheet:https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly

Check out the InsectXaminer Episode about spotted lanternfly adults and egg masses! Available here:https://ag.umass.edu/landscape/education-events/insectxaminer

From the MA Department of Agricultural Resources:

Fact Sheet and Map of Locations in MA:https://massnrc.org/pests/pestFAQsheets/spottedlanternfly.html

Spotted Lanternfly Management Guide for Homeowners in Infested Areas:https://massnrc.org/pests/linkeddocuments/SLFHomeownerMgmtGuide.pdf

• Asian Longhorned Beetle: (Anoplophora glabripennis, ALB) Look for signs of an ALB infestation which include perfectly round exit holes (about the size of a dime), shallow oval or round scars in the bark where a female has chewed an egg site, or sawdust-like frass (excrement) on the ground nearby host trees or caught in between branches. Be advised that other, native insects may create perfectly round exit holes or sawdust-like frass, which can be confused with signs of ALB activity. 

The regulated area for Asian longhorned beetle is 110 square miles encompassing Worcester, Shrewsbury, Boylston, West Boylston, and parts of Holden and Auburn.  If you believe you have seen damage caused by this insect, such as exit holes or egg sites, on susceptible host trees like maple, please call the Asian Longhorned Beetle Eradication Program office in Worcester, MA at 508-852-8090 or toll free at 1-866-702-9938.

To report an Asian longhorned beetle find online or compare it to common insect look-alikes, visit: http://massnrc.org/pests/albreport.aspx or https://www.aphis.usda.gov/pests-diseases/alb/report .

• Emerald Ash Borer: (Agrilus planipennis, EAB) has been detected in at least 11 out of the 14 counties in Massachusetts.A map of these locations across the state may be found here:https://ag.umass.edu/fact-sheets/emerald-ash-borer . Additional information about this insect is provided by the MA Department of Conservation and Recreation, here:https://storymaps.arcgis.com/stories/b60f63199fa14805a8b9f7c82447a25b .

This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and has been reported in cultivated olive (Olea europaea). Signs of an EAB infested tree may include D-shaped exit holes in the bark (from adult emergence), “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath), and serpentine galleries visible through splits in the bark, from larval feeding beneath. It is interesting to note that woodpeckers are capable of eating 30-95% of the emerald ash borer larvae found in a single tree (Murphy et al. 2018). Unfortunately, despite high predation rates, EAB populations continue to grow. However, there is hope that biological control efforts will eventually catch up with the emerald ash borer population and preserve some of our native ash tree species for the future.

• Winter Moth: (Operophtera brumata) data since 2017 has indicated that the winter moth population in eastern Massachusetts has been on the decline while the percent of winter moth pupae parasitized by Cyzenis albicans has increased! Dr. Joseph Elkinton’s laboratory at UMass Amherst has released this biological control agent of winter moth since 2005 and conducted the rigorous sampling required to determine where the insect has established and what its impact on the winter moth population has been at multiple sites in eastern MA.

The take-home point? Do not worry about winter moth this spring! In fact, management of this insect in landscaped settings will likely not be necessary in most locations. Blueberry growers may still, on the other hand, be interested in scouting and continuing to monitor for this insect, as only very low numbers of winter moth caterpillars might be tolerated in that system.

For blueberry and apple growers in Rhode Island, check out this winter moth update from Heather Faubert (University of Rhode Island) for April 13, 2023: https://web.uri.edu/ipm/2023/04/winter-moth-update-april-13-2023/ .

In recent years, it is worth-while to note that some areas on the Cape and other locations in eastern MA have reported noticeable native cankerworm populations in the spring, which are often confused for winter moth. Read more about cankerworms in the spring scouting list below.

• Jumping Worms: Amynthas spp. earthworms, collectively referred to as “jumping or crazy or snake” worms, overwinter as eggs in tiny, mustard-seed sized cocoons found in the soil or other substrate (ex. compost). Immature jumping worms hatch from their eggs by approximately mid-to-late May. It may be impossible to see them at first, and it may be more likely that jumping worms are noticed when the first adults begin to appear at the end of May and in June. It is easy to misidentify jumping worms (ex. mistake European earthworms for jumping worms) if only juveniles are found. In August and September, most jumping worms have matured into the adult life stage and identification of infestations is more likely to occur at that time of year.

For More Information:

UMass Extension Fact Sheets:

• Earthworms in Massachusetts – History, Concerns, and Benefits: https://ag.umass.edu/landscape/fact-sheets/earthworms-in-massachusetts-history-concerns-benefits
• Jumping/Crazy/Snake Worms – Amynthas spp.: https://ag.umass.edu/landscape/fact-sheets/jumpingcrazysnake-worms-amynthas-spp
• A Summary of the Information Shared at UMass Extension’s Jumping Worm Conference in January 2022: https://ag.umass.edu/news-events/highlights/jumping-worms-conference
• Invasive Jumping Worm Frequently Asked Questions (Over 70 Questions and their Answers): https://ag.umass.edu/landscape/fact-sheets/invasive-jumping-worm-frequently-asked-questions

Spring Scouting Suggestions & Preparation for Upcoming Tree & Shrub Insects (Native and Invasive):

• Bagworm:Thyridopteryx ephemeraeformis is a native species of moth whose larvae construct bag-like coverings over themselves with host plant leaves and twigs. This insect overwinters in the egg stage, within the bags of deceased females from last season. Eggs may hatch and young larvae are observed feeding around mid-June, or roughly between 600-900 GDD’s. Now is the time to scout for and remove and destroy overwintered bags. More information can be found here:https://ag.umass.edu/landscape/fact-sheets/bagworm

• Black Turpentine Beetle: Dendroctonus terebrans adults may begin to be active between mid-April to mid-May. Host plants include: black pine (Pinus thunbergiana), eastern white pine (Pinus strobus), Japanese black pine (Pinus thunbergii), loblolly pine (Pinus taeda), pitch pine (Pinus rigida), red spruce (Picea rubens), Scots pine (Pinus sylvestris), and slash pine (Pinus elliottii).

  This is one of the largest native North American bark beetles. In the northern parts of its extensive range, the black turpentine beetle overwinters as an adult in the bark of its hosts. In the southern portions of its range, all life stages may be present throughout the year. Egg laying and feeding is usually kept to the basal 6 feet of the host plant. Mated pairs of adult beetles work to excavate galleries that may be 9.8 inches wide and 11.8 inches long. 100-200 eggs may be laid on one side of the gallery. Once hatched, larvae feed in groups on the inner bark. Fully grown larvae are legless, white, and almost 1/2 inch in length. Pupation occurs and adults eventually emerge from the bark to re-infest the same tree, or disperse to another susceptible host.

  Stumps and buttress roots of freshly cut trees are favored by this insect. Attacked trees may exhibit browning of needles and oozing of large masses of pitch. Masses of pitch (pitch tubes) may cover holes in the trunk and may be considerably larger than those of southern pine beetle. Pitch hardens and is first white but may turn red as it ages. Pitch is irregular in shape and up to 1.6 inches in diameter. Pitch tubes not visible when the area below soil line is attacked. Healthy trees are usually not attacked, however it has been reported on occasion. 

  Check drought-stressed or otherwise stressed trees for needles turning light green to rust color. Check the lower 6 feet, particularly the lower 18 inches of the trunk for 1.6 inch in diameter pitch tubes or small entrance holes from the adults. Reddish-brown boring dust may be found near the base of the tree as well.

• Boxwood Leafminer: Monarthropalpus flavus partly grown fly larvae overwinter in the leaves of susceptible boxwood. Yellowish mines may be noticeable on the undersides of leaves. This insect grows rapidly in the spring, transforming into an orange-colored pupa. After pupation, adults will emerge and white colored pupal cases may hang down from the underside of leaves where adults have emerged. Adults may be observed swarming hosts between 300-650 GDD’s, or roughly the end of May through June. Most cultivars of Buxus sempervirens and B. microphylla are thought to be susceptible. If installing new boxwoods this spring, resistant cultivars such as ‘Vardar Valley’ and ‘Handsworthiensis’ are good choices at sites where this insect has been a problem. For more information, visit: https://ag.umass.edu/landscape/fact-sheets/boxwood-leafminer
• Boxwood Mite: Eurytetranychus buxi overwinter as tiny eggs on boxwood leaves and hatch mid-spring. These mites are tiny (about the size of a period) and difficult to detect. Feeding may cause plants to appear off-color. If management is deemed necessary, the timing for treatment may be between 245-600 GDD’s or roughly the beginning of May.
• Boxwood Psyllid: Psylla buxi feeding can cause cupping of susceptible boxwood leaves. Leaf symptoms/damage may remain on plants for up to two years. English boxwood may be less severely impacted by this pest. Eggs overwinter, buried in budscales, and hatch around budbreak of boxwood. Eggs may hatch around 80 GDD’s. While foliar applications may be made between 290-440 GDD’s, the damage caused by this insect is mostly aesthetic. Therefore, typically, management is not necessary. For more information, visit: https://ag.umass.edu/landscape/fact-sheets/boxwood-psyllid .
• Cankerworms: Alsophila pometaria (fall cankerworm) and Paleacrita vernata (spring cankerworm) are often confused for winter moth (Operophtera brumata). Cankerworm populations in eastern MA, particularly on areas of Cape Cod, were confused for winter moth in 2019. Spring cankerworm adults are active in February and March, and fall cankerworm adults are active in late November into early December. During these times, both species lay eggs. These native insects most commonly utilize elm, apple, oak, linden, and beech. Eggs of both species hatch as soon as buds begin to open in the spring. Caterpillars occur in mixed populations and are often noticeable by mid-May in MA. Young larvae will feed on buds and unfolding leaves. There are two color forms (light green and dark) for caterpillars of both species. Like winter moth, they will drop to the soil to pupate. This usually occurs in June. Fall cankerworm larvae have three pairs of prolegs (one of which is small so it is sometimes referred to as ½) and spring cankerworm have two pairs. (Winter moth caterpillars also have 2 pairs of prolegs.) If populations are large and damage is noticeable on hosts, reduced risk insecticides such as Bacillus thuringiensis Kurstaki or spinosad may target larvae between approximately 148-290 GDD’s.

  For more information, visit: https://ag.umass.edu/landscape/fact-sheets/fall-cankerworm and

• Dogwood Borer: Synanthedon scitula is a species of clearwing moth whose larvae bore not only into dogwood (Cornus), but hosts also include flowering cherry, chestnut, apple, mountain ash, hickory, pecan, willow, birch, bayberry, oak, hazel, myrtle, and others. Kousa dogwood appear to be resistant to this species. Signs include the sloughing of loose bark, brown frass, particularly near bark cracks and wounds, dead branches, and adventitious growth. The timing of adult emergence can be expected when dogwood flower petals are dropping and weigela begins to bloom. Adult moth flights continue from then until September. Emergence in some hosts (ex. apple) appears to be delayed, but this differs depending upon the location in this insect’s range. Eggs are laid singly, or in small groups, on smooth and rough bark. Female moths preferentially lay eggs near wounded bark. After hatch, larvae wander until they find a suitable entrance point into the bark. This includes wounds, scars, or branch crotches. This insect may also be found in twig galls caused by other insects or fungi. Larvae feed on phloem and cambium. Fully grown larvae are white with a light brown head and approx. ½ inch long. Pheromone traps and lures are useful for determining the timing of adult moth emergence and subsequent management.

• Dogwood Sawfly: Macremphytus tarsatus has one generation per year. The larvae of the dogwood sawfly overwinter in decaying wood and occasionally compromised structural timber. An overwintering "cell" is created in this soft wood. Pupation occurs in the springtime and adults can take a lengthy time to emerge, roughly between late May and July. 100+ eggs are laid in groups on the underside of leaves. Eggs hatch and the larvae feed gregariously, initially skeletonizing leaves. As the caterpillars grow in size, they are capable of eating the entire leaf with the exception of the midvein. Larval appearance varies greatly throughout instars, so much so that one might mistake them for multiple species. Early instars are translucent and yellow, but as the caterpillars grow they develop black spots (over yellow) and become covered in a white powder-like material. Larvae and their shed skins may resemble bird droppings. Full grown larvae begin to wander in search of a suitable overwintering location. Rotting wood lying on the ground is preferred for this.

  Foliage of dogwood, especially gray dogwood (Cornus racemosa) may be impacted. Skeletonizes leaves at first, then eats all but the midvein.

• Eastern Spruce Gall Adelgid: Adelges abietis is a pest of Norway spruce primarily, but occasionally damages other spruce species such as Colorado blue, white, and red spruce. This adelgid overwinters as a partially grown female, often referred to as a stem mother. This overwintering individual matures around bud break and lays 100-200 eggs. The eastern spruce gall adelgid may be targeted for management between 22-170 GDD’s, base 50°F (mid-April to early-May).

The eastern spruce gall adelgid may be targeted for management between 22-170 GDD’s, base 50°F (mid-April to early-May).

Egg hatch typically occurs when wild cherry leaves begin to unfold and young caterpillars may emerge by late-April through the first two weeks in May (90-190 GDD’s).

This insect is non-native, and was introduced into the United States from Europe before 1900. Galls are small, sometimes pineapple shaped/variable, but produced on the basal portion of the shoots, such that the twig extends beyond the gall. Twig dieback may occur.

• Eastern Tent Caterpillar: Malacosoma americanum eggs overwinter on host plant twigs. Egg hatch typically occurs when wild cherry leaves begin to unfold and young caterpillars may emerge by late-April through the first two weeks in May (90-190 GDD’s). Susceptible hosts include cherry and crabapple. Other host plants whose leaves are fed upon by this native insect can include apple, ash, birch, willow, maple, oak, poplar, and witch-hazel. Prune off and remove egg masses from ornamental host plants by early spring. Eastern tent caterpillars are native to Massachusetts and have many associated natural enemies (parasites and predators) that help regulate populations. Unless these caterpillars are actively defoliating specimen trees in a landscaped setting, we can coexist with this particular herbivore native to our forests.
• Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce, and fir. The elongate hemlock scale may overwinter in various life stages, and overlap of many developmental stages at any given time can be observed throughout much of the season.

Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F.

Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F. Nitrogen fertilizer applications may make elongate hemlock scale infestations worse.

For more information, visit: https://ag.umass.edu/landscape/fact-sheets/elongate-hemlock-scale .

• Elm Leaf Beetle: Xanthogaleruca (formerly Pyrrhalta) luteola is found on American elm (Ulmus americana; not preferred), Chinese Elm (Ulmus parvifolia; not preferred), English Elm (Ulmus procera; preferred host), Japanese Zelkova (Zelkova serrata), and Siberian Elm (Ulmus pumila; preferred host).

This species was accidentally introduced into the eastern United States early in the 1800's. Since then, it has been found throughout the USA anywhere elms are located. It also occurs in eastern Canada. The adult elm leaf beetle overwinters in protected areas, such as the loose bark of trees, but can also be a nuisance when it tries to invade homes in search of overwintering protection. Beetles will try to enter houses or sheds in the fall. 

In the spring, the adult beetles will fly back to the host plant and chew small, semi-circular holes in the leaves. The adult female can lay 600-800 yellow eggs in her life. Eggs are laid in clusters on the leaves and resemble pointy footballs. Larvae are tiny, black, and grub-like when they hatch from the egg. Young larvae will skeletonize the undersides of leaves. As they grow in size, the larvae become yellow-green with rows of black projections. Oldest larvae may appear to have two black stripes along their sides, made from the black projections. There are 3 larval instars. Mature larvae will wander down the trunk of the host tree and pupate in the open on the ground at the tree base or in cracks and crevices in the trunk or larger limbs. They spend approximately 10 or so days as a pupa, and then the adults emerge. Those adults will fly to the foliage of the same host plant or other adjacent potential hosts in the area, where they will lay eggs. In the fall, the adults will leave the host plant in search of overwintering shelter. In most locations in the USA, two generations of this insect are possible per year. In warmer locations, 3-4 generations per year are possible.

Leaves are skeletonized by the larvae. Skeletonization may cause the leaf to turn brown or whitish. Adults are capable of chewing through the leaf, often in a shothole pattern. When in very large populations, they are capable of completely defoliating plants. Populations of this insect can fluctuate from year to year, and often management is not necessary if populations are low. However, defoliation for consecutive seasons may lead to branch dieback or death of the entire tree.

• Euonymus Scale: Unaspis euonymi is an armored scale that can be found on euonymus, holly, bittersweet, and pachysandra. This insect can cause yellow spotting on leaves, dieback, and distorted bark. For crawlers, early June timing is suggested between 533-820 GDD’s for management. (Eggs begin to hatch in early June.)
• European Pine Sawfly: Neodiprion sertifer overwinters in the egg stage. Eggs are laid by females the previous season by cutting slits in needles using their ovipositors and depositing 6-8 eggs in each of 10-12 needles.
• Fletcher Scale: Parthenolecanium fletcheri is a soft scale pest of yew, juniper, and arborvitae. Feeding scales, especially on yew, result in honeydew and sooty mold, needle yellowing, and at times, premature needle drop. There is one generation per year. Overwintered second instar nymphs can be targeted between 38-148 GDD’s, base 50°F. Nymphs develop and adult females lay eggs (on average 500-600) in May that hatch by June. Dead females conceal egg masses beneath. Crawlers migrate short distances to branches and may be concentrated on certain branches of a particular plant.

Egg hatch occurs from late-April to mid-May and caterpillars become active roughly between 78-220 GDD, base 50°F. The primary host in MA is Mugo pine but it can be found on Scots, red, jack, and Japanese red pine. It is also found on white, Austrian, ponderosa, shortleaf, and pitch pine when planted near the aforementioned species.  This dark colored caterpillar feeds in tight groups and small numbers can be pruned or plucked out of host plants and destroyed. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis kurstaki is not effective against sawflies.

• Forest Tent Caterpillar: Malacosoma disstria egg hatch occurs between 192-363 GDD’s, base 50°F, by mid-late May and caterpillars may be active for at least 5-6 weeks following. Susceptible hosts whose leaves are fed on by this insect include oak, birch, ash, maple, elm, poplar, and basswood. This native insect has many natural enemies, including some very effective pathogens that typically regulate populations. However, outbreaks of this insect can occur on occasion.
• Hemlock Looper: Two species of geometrid moths in the genus Lambdina are native insects capable of defoliating eastern hemlock, balsam fir, and white spruce. Adult moths lay their eggs on the trunk and limbs of hosts in September and October, and eggs will hatch by late May or early June. (L. fiscellaria caterpillars may be active between 448-707 GDD’s.) Monitor susceptible hosts for small, inch-worm like caterpillars. Where populations are low, no management is necessary. Hemlock loopers have several effective natural enemies.
• Honeylocust Plant Bug: Diaphnocoris chlorionis feeding results in tiny yellowish-brownish spots on leaves, leaf distortion, and in some cases, defoliation. (There are at least 7 species of plant bugs that feed on honeylocust, Gleditsia triacanthos.) There is one generation per year. Immatures and adults feed on foliage and light to moderately damaged foliage may persist throughout the growing season. Honeylocust plant bugs overwinter as eggs laid just beneath the bark surface of 2 and 3 year old twigs. Eggs hatch just after vegetative bugs of the host begin to open. Young nymphs crawl to the opening leaflets and begin feeding and the most significant damage occurs at that time, when the insect is hidden from view. Nymphs develop into adults around May-July. This insect can be targeted between 58-246 GDD’s, base 50°F.
• Imported Willow Leaf Beetle: Plagiodera versicolora adult beetles overwinter near susceptible hosts. Adult beetles will chew holes and notches in the leaves of willow once they become available. Females lay yellow eggs in clusters on the undersides of leaves. Larvae are slug-like and bluish-green in color. They will feed in clusters and skeletonize the leaves. Most plants can tolerate the feeding from this insect, and foliage will appear brown. Repeated yearly feeding can be an issue, in which case management of the young larvae may be necessary. Take care with treatment in areas near water. 

Check out Episode 4 of InsectXaminer to see the imported willow leaf beetle in action: https://ag.umass.edu/landscape/education-events/insectxaminer

• Japanese Cedar Longhorned Beetle: Almost on an annual basis, UMass Extension receives questions about evidence of wood boring beetle attack on eastern redcedar and similar hosts, including but not limited to: American arborvitae, Atlantic white cedar, common juniper, false arborvitae, Hinoki cypress, Japanese cedar, Leyland cypress, and others. The culprit could be the Japanese cedar longhorned beetle (Callidiellum rufipenne) or our native cedar tree borer (Semanotus ligneus). C. rufipenne is discussed here. We recommend submitting samples of the damaged plant material and any insect life stages to the UMass Plant Diagnostics Laboratory: https://ag.umass.edu/services/plant-diagnostics-laboratory/tree-shrub-diagnostics-pinewood-nematode-assay .

The Japanese cedar longhorned beetle was first detected in Washington state in 1954. This wood boring beetle is found in conifers belonging to the cypress family. Primary hosts noted for this species include arborvitae, cypress, juniper, and cedar (Chamaecyparis). Adult beetles are small, approximately ¼ to ½ inch in length with long antennae (males have antennae that are slightly longer than their bodies; females have shorter antennae). The females have reddish brown elytra (hardened wings) and the males appear darker in color (shiny blue-black) with red visible on the “shoulders” of the beetle (just behind the thorax). There is one generation per year, although in colder locations it may take 2 years to complete its life cycle. Once the females emerge from their host, they begin to lay eggs in the cracks and crevices of bark during their 20-day life span. Each female lays approximately 20 eggs (Shibata, 1994). Eggs hatch within 2 weeks and the larvae bore beneath the bark, creating tunnels or galleries as they feed in the phloem and cambium layers of the tree or shrub. Larvae are cream colored with 3 pairs of thoracic legs and grow up to approximately ¾ inch in length. As many as 10 larvae may be found in a single arborvitae branch. When the larvae are mature, they enter the xylem where they pupate, which is suspected to occur in the fall. The Japanese cedar longhorned beetle is thought to overwinter as an adult within the host plant, and emerges early the next season in the spring (Hoebeke, 1999; Humphreys and Allen, 2000; Maier and Lemmon, 2000). However, depending upon geographic location, there is discrepancy between sources regarding the overwintering life stage of this insect.

The feeding damage from the larvae of this insect causes branch dieback which may not be noticed until the following spring after initial infestation. Other signs of this insect include frass found near galleries and splits in the bark and 1/8 inch, oval exit holes. Bark may appear puckered where larval mining occurs, and frass can be seen within the mines if they are exposed by splits in the bark. Frass-packed galleries occur in the cambium and xylem. Monitor for this insect, especially in Suffolk and Nantucket Counties in Massachusetts. May also be present elsewhere in the state. Look for branch dieback on susceptible hosts in the spring. Look for bark splits, galleries, frass, and oval exit holes. With caution and the proper tools, slice open dying branches to look for galleries in the cambium and xylem and also potentially expose larvae, pupae, or adult beetles. 

Borers may be preferentially attracted to stressed plants. Take precautions to avoid plant stress, such as proper planting and site selection. Prune out and destroy infested branches prior to adult emergence in the spring. In Japan, Shibata (1994) determined that approximately 53% of pre-adult Japanese cedar longhorned beetles succumb to disease or parasitism by a suite of natural enemies. Most of the larval mortality occurs due to (as of yet) unidentified diseases; some pupal mortality occurs due to disease as well. Before pupation, larvae are also killed by two important parasitoids - Doryctes yogoi and Ischnoceros sapporensis. Two species of parasitoids from the pupal cells of Japanese cedar longhorned beetles are also known - Baeacis semanoti and Rhimphoctona spp. (Invasive Species Compendium; CABI). The full impact of natural enemies on this insect in the United States is not completely understood.

• Lecanium Scales (Oak): Parthenolecanium quercifex overwinters as a second instar nymph on oak twigs. Females will begin feeding and mature in the spring, from mid-April to early May and eggs may be laid between late May and into June. Eggs hatch in June or early July and crawlers migrate to host plant leaves where they spend the summer and migrate as second instars back to host plant twigs in the fall. Mid-April to early-May (35-145 GDD’s) for dormant oil applications.
• Lilac Borer: Podosesia syringae is a clearwing moth pest of lilac, privet, fringetree, and ash. (It is also known as the ash borer, not to be confused with the emerald ash borer.) Adults mimic paper wasps. Larvae are wood-boring, and signs and symptoms include branch dieback, holes, and occasionally, sawdust-like frass accumulated on bark. Larvae bore into stems, trunks, and branches, chewing an irregularly shaped entrance hole. Peak adult moth flights may occur in the northern portion of this insect’s range in June and is usually over by August 1st. Pheromone traps can be used to time adult emergence. Adult females lay flattened, oval, and tan eggs that are deposited singly or in clusters on bark crevices, ridges, and sometimes smooth bark; but usually laid in or near wounds in the bark. On average, 395 eggs are laid by each female. After hatch, larvae chew into the bark and feed laterally and then vertically in phloem tissue. Larvae overwinter in tunnels in the final instar and resume feeding in the spring. Adults emerge through a round exit hole (4-5 mm. in diameter). This insect may be targeted between 200-299 GDD’s, base 50°F.
• Lily Leaf Beetle:Lilioceris liliiadults overwinter in sheltered places. As soon as susceptible hosts such as Lilium spp. (Turk’s cap, tiger, Easter, Asiatic, and Oriental lilies) and Fritillaria spp. break through the ground, the adult lily leaf beetles are known to feed on the new foliage. (Note: daylilies are not hosts.) Adult lily leaf beetles were observed to be active in Hanson, MA on 4/14/2023. Typically, in May, mating will occur and each female will begin to lay 250-450 eggs in neat rows on the underside of the foliage. If there are only a few plants in the garden, hand picking and destroying overwintering adults can help reduce local garden-level populations at that time.  

Check out Episode 3 of InsectXaminer to see the lily leaf beetle in action:https://ag.umass.edu/landscape/education-events/insectxaminer

• Magnolia Scale: Neolecanium cornuparvum overwinters as first instar nymphs which are elliptical, and dark slate gray in color and can usually be found on the undersides of 1 and 2 year old twigs. Nymphs may molt by late April or May and again by early June at which time the scales may be purple in color. Eventually nymphs secrete a white powdery layer of wax over their bodies.
  • For more information, visit: https://ag.umass.edu/landscape/fact-sheets/magnolia-scale .

• Pitch Mass Borer: Synanthedon pini is a native clearwing moth whose larvae feed within various pines and spruce. Feeding by the larvae (caterpillars) of this insect causes pitch masses to form on host plants. Two or three years are required for this insect to complete its life cycle, with adult moths present during the summer. Adult pitch mass borer moths may resemble wasps. Adult males and females are blue/black from above, marked with a patch of red/orange on the underside of the abdomen, with some orange on the top of the fourth abdominal segment. Orange is also found along the sides of the abdomen. Forewings are black/blue in color and opaque with wing length of 0.47 to 0.59 inches. Adults are said to emerge, mate, and females lay eggs on their hosts some time in July. By the late summer, the larvae (immatures; caterpillars) bore into their host plant, tunneling through the trunks, often directly beneath a branch. Larvae have uniformly dark brown heads, white bodies, and prolegs with rows of 6-8 crochets on the bottom of their "feet". At the site of the borer wound, large amounts of pitch exude from the tree in a hemispherical mass above the larval tunnels. Larvae continue to feed and develop in the tree through the following year, and it is thought that caterpillars may take up to two years to mature. Masses may be 3-4 inches in diameter. Pupation occurs in a subsequent end of May through June in time for adult emergence by July and August. Pupal cells are formed within the pitch mass and lined with silk (Beuttenmüller, 1901). Pupae are 0.73 inches long and light brown in color (Kellicott, 1881).

  Adult moths are active during the summer. Following egg laying and egg hatch, the larvae tunnel under the bark to the cambium. Obvious, large globs of pitch appear on trunks. Occurs sporadically on individual trees. Host trees with active caterpillars have pitch masses that may appear coated in a white, powdery substance. Larvae may also preferentially bore into the host beneath a broken branch or scar. This insect will attack large trees, up to 30-40 feet from the ground. Healthy trees are also preferentially utilized. Overall damage to the health of the host tree is typically not extensive, and therefore chemical management of this insect is often unnecessary.

  Pitch can be removed and the single larva within destroyed. Physical/mechanical management of this insect, if it can be safely done, is a great way to manage the pitch mass borer on individual specimen trees. The act of just pulling the caterpillar from its pitch mass will kill it - much to the frustration of history's entomologists looking to study them - as soon as contact of the pitch is made with the caterpillar's body and hardens and adheres to them. Parasitism by natural enemies is reported to be relatively common. Parasitic wasps in the family Eulophidae are noted but not specified, as well as a caterpillar-eating species of fly (Engelhardt, 1946).

• Snowball Aphid: Neoceruraphis viburnicola eggs overwinter on viburnum twigs and buds. Eggs hatch and this aphid becomes active on certain species of viburnum roughly between 148-298 GDD’s or around redbud bloom. This insect is particularly noticeable on V. opulus, V. prunifolium, and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage. Damage caused by this insect pest is mostly aesthetic.
• Spruce Bud Scale: Physokermes piceae is a pest of Alberta and Norway spruce, among others. Immatures overwinter on the undersides of spruce needles, dormant until late March. Immatures overwinter on the undersides of spruce needles, dormant until late March. By April, females may move to twigs to complete the rest of their development. Mature scales are reddish brown, globular, 3 mm. in diameter, and found in clusters of 3-8 at the base of new twig growth. They closely resemble buds and are often overlooked. Crawlers are present around June.
• Spruce Spider Mite: Oligonychus ununguisis a cool-season mite that becomes active in the spring from tiny eggs that have overwintered on host plants. Hosts include spruce, arborvitae, juniper, hemlock, pine, Douglas-fir, and occasionally other conifers. This particular species becomes active in the spring and can feed, develop, and reproduce through roughly June. When hot, dry summer conditions begin, this spider mite will enter a summer-time dormant period (aestivation) until cooler temperatures return in the fall. This particular mite may prefer older needles to newer ones for food. Magnification is required to view spruce spider mite eggs. Tapping host plant branches over white paper may be a useful tool when scouting for spider mite presence. (View with a hand lens.) Spider mite damage may appear on host plant needles as yellow stippling and occasionally fine silk webbing is visible.

• Viburnum Leaf Beetle: Pyrrhalta viburni is a beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. Larvae are present and feeding on plants from approximately late April to early May until they pupate some time in June. Adult beetles emerge from pupation by approximately mid-July and will also feed on host plant leaves, mate, and lay eggs at the ends of host plant twigs where they will overwinter. This beetle feeds exclusively on many different species of viburnum, which includes, but is not limited to, susceptible plants such as V. dentatum, V. nudum, V. opulus, V. propinquum, and V. rafinesquianum. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum, and V. sieboldii. More information about viburnum leaf beetle may be found athttp://www.hort.cornell.edu/vlb/ and here: https://ag.umass.edu/landscape/fact-sheets/viburnum-leaf-beetle .
• White Spotted Pine Sawyer (WSPS): Monochamus scutellatus adults can emerge in late May throughout July, depending on local temperatures. This is a native insect in Massachusetts and is usually not a pest. Larvae develop in weakened or recently dead conifers, particularly eastern white pine (Pinus strobus). However, the white spotted pine sawyer looks very similar to the invasive Asian Longhorned Beetle, Anoplophora glabripennis, ALB. ALB adults do not emerge in Massachusetts until July and August. Beginning in July, look for the key difference between WSPS and ALB adults, which is a white spot in the top center of the wing covers (the scutellum) on the back of the beetle. White spotted pine sawyer will have this white spot, whereas Asian longhorned beetle will not. Both insects can have other white spots on the rest of their wing covers; however, the difference in the color of the scutellum is a key characteristic. See the Asian longhorned beetle entry above for more information about that non-native insect.
• Woolly Apple Aphid: Eriosoma lanigerum may be found on apple, crabapple, hawthorn, mountain ash, Pyracantha, and elm hosts. The primary (winter) host is elm, on which aphids infest emerging spring leaves, causing leaves to curl or close into stunted, rosette-like clusters found at twig tips. On apple and crabapple, this species of aphid colonizes roots, trunks, and branches in the summer and is commonly found near previous wounds or callous tissue. On roots, the aphids cause swelled areas which can girdle and kill roots. The aphids, when found in above ground plant parts such as elm leaves, are covered with white wax. Eggs are the overwintering stage on elm, which hatch in the spring in time for the nymphs to infest new elm foliage. Following a few generations on elm, the aphids will develop into a winged form, which will disperse and seek out apple and crabapple. Multiple generations will occur on these alternate hosts in the summer and by the fall, a winged form will return to elm and mated females will lay eggs near elm buds. These aphids are a favorite snack for insect predators such as the multicolored Asian lady beetle, Harmonia axyridis.

• Woolly Elm Aphid: Eriosoma americanum females lay a single egg in the cracks and crevices of elm bark, where the egg overwinters. Eggs hatch on elm in the spring as leaves are unfolding. Aphids may be active from 121-246 GDD’s, base 50°F on elm. Aphids may be active from 121-246 GDD’s, base 50°F on elm. A young, wingless female hatched from the egg feeds on the underside of leaf tissue. This female aphid matures and gives birth to 200 young, all females, without mating. These aphids feed, and the elm leaf curls around them and protects them. By the end of June, winged migrants mature and find serviceberry hosts. Another set of females is produced. These new females crawl to and begin feeding on the roots of serviceberry. Multiple generations occur on the roots of serviceberry through the summer.

Concerned that you may have found an invasive insect or suspicious damage caused by one? Need to report a pest sighting? If so, please visit the Massachusetts Introduced Pests Outreach Project:http://massnrc.org/pests/pestreports.htm .

Reported by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program

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