During the nineteenth century the theories of evolution reached wider public profile, and it was an age of scientific change, with the study of natural history becoming very popular. Victorians were fascinated by beetles and butterflies, and they were not only studied, but also featured in Victorian art and fashion.1
It has been suggested that Britain became “obsessed with insects”1, and in the fungi collection at Cumberland House there are some deceased insect pupae and a whole caterpillar. But how did they meet their grisly fates, and what has it got to do with fungi?
Fungi on Moth Pupae
Two specimens have been discovered in the fungi collection which have details of their growth on the pupae of moths, that were once kept in a breeding case. The first is the Scarlet Caterpillarclub Fungus, Cordyceps militaris, which was found on the pupa of the moth Hadena chenopodii (now Anarta trifolii), more commonly known as the Nutmeg. It was found dead in a breeding cage, in Bognor Regis, West Sussex, on the 1st of September, 1896 (Fig. 1). To me it looks a bit like a fish.
The Scarlet Caterpillarclub is the most common of the Cordyceps species recorded in the British Isles and can be mainly found on woodland edges and in grassland, surfacing as an orange club.2 It parasitises its hosts, the underground pupae of moths, but some species may also parasitise other fungi such as false truffles and puffballs, or insects such as ants.2
The other specimen is another pupa of Hadena chenopodii, or Anarta trifolii, found dead in a breeding case on the same day, with the fungus Isaria farinosa (Fig. 2). In this case the specimen has been housed in a small round pot, which the corner of the label had been shut in. The fungus causes death or harm to insects (entomopathogenic) and has multiple hosts and a worldwide distribution.3
The Nutmeg moth (Fig. 3) that would have emerged from these pupae occurs most commonly today in south-east England, appearing from May to September.4 As larvae they particularly like to eat orache and goosefoot.4
The Vegetable Caterpillar from New Zealand
One of the specimens in the collection looks very strange indeed and is accompanied by a letter from a curios dealer in New Zealand. Curios shops would have been full of unusual and bizarre objects, and Victorian curio cabinets would have contained the same, often housing a collection amassed over someone’s lifetime.6
In this case the curio is a caterpillar with a fungus growing out of its head! Mummified caterpillars like these were sold as a curio in the early 20th century to tourists.7 The fungus with this one has been named as Sphaeria robertsiana in the accompanying letter, which is now known as Ophiocordyceps robertsii, or the Vegetable Caterpillar (Fig. 4). This was the first fungus named in New Zealand.8
The caterpillars of leaf-litter dwelling moths are turned into mummies once the fungus has invaded them, and spores are shed from a fruiting spike sent up above the forest floor (Fig. 5). To complete the fungal life cycle, other caterpillars eat the spores as they feed on the leaf litter.7
Had the caterpillar in the collection avoided such an attack from this fungus it would have transformed into New Zealand’s largest moth, the Pūriri moth, or ghost moth (Fig. 6).
This work is funded by the Headley Trust.
References:
1. Kohlt, F. (2016). Creepy Victorians. How nineteenth century Britain became obsessed with insects. [Blog Post]. Retrieved from Insect Week website: Creepy Victorians | Insect Week
2. Cordyceps militaris. (n.d.). Retrieved from First Nature website: Cordyceps militaris, Scarlet Caterpillarclub fungus (first-nature.com)
3. Weng, Q., Zhang, X., Chen, W., & Hu, Q. (2019). Secondary Metabolites and the Risks of Isaria fumosorosea and Isaria farinosa. Molecules, 24(4), 664.
4. The Nutmeg. (n.d.). Retrieved from UKmoths website: The Nutmeg | UKmoths
5. “Nutmeg Moth”, July 29, 2021, Nutmeg Moth Flowers – Free photo on Pixabay, by Margareito, Margareito | Pixabay
6. The Victorian art of Curio collecting. (29 May, 2017). Retrieved from: The Victorian art of Curio collecting (grimsdyke.com)
7. Ophiocordyceps robertsii. Wikimedia Foundation. Last modified March 30, 2021. Retrieved from: Ophiocordyceps robertsii – Wikipedia
8. Relph, D. Caterpillar Killer. (1991). Retrieved from New Zealand Geographic website: Caterpillar killer | New Zealand Geographic (nzgeo.com)
9. “Aenetus virescens female LCR”, November 26, 2011, File:Aenetus virescens female LCR.jpg – Wikimedia Commons, by Birgit E. Rhode, Licenced under CC BY 4.0, Creative Commons — Attribution 4.0 International — CC BY 4.0