Scarlet Caterpillar Club

Here’s a thrill. It’s the pupa of a moth, which has been been infected with a fungus called Scarlet Caterpillar Club, Cordyceps militaris, which is growing out of its body. It was found by one of the people on our Devon Fungus Group foray to Mamhead in South Devon.

Scarlet Caterpillar fungus - Cordyceps militaris - The Hall of Einar - photograph (c) David Bailey (not the)

The fungus is dissolving the remains of the pupa, meaning it will never complete its transition from caterpillar to moth. It’s a fungus I found as a child on Saddleworth Moor in 1976 as part of a foray by the Oldham and Microscopical and Natural History Society. My childhood was spent with gentlemen naturalists in tweeds with briar pipes and loft conversions full of their butterfly collections, and rebellious lady naturalists who were experts in fungus gnats. It was fabulous. Fashions have changed but I’m just as passionate about a fungus that grows on a caterpillar as I was then.

Here’s my childhood nature notebook entry from 1 November 1976:

Cordyceps militaris - The Hall of Einar - photograph (c) David Bailey (not the)

Walking around Emsworthy Mire on Dartmoor I find another one.

Scarlet Caterpillar Club Fungus - The Hall of Einar - photograph (c) David Bailey (not the)

They have a strange bobbly texture unlike anything else. These bobbles are called stroma, inside of which are the fruit bodies, the peritheca.

Cordyceps militaris has strange chemistry, including Cordycepin, which shifts the body clock which regulates day and night, your circadian rhythm. Sounds like a great thing if you’ve got jet lag.

I decide to dig it up to see if I can find the pupa. Wow, no, it’s on a caterpillar.

Scarlet Caterpillar Club Fungus - The Hall of Einar - photograph (c) David Bailey (not the)

Here it is in James Sowerby’s Coloured figures of English fungi or mushrooms from 1797:

James Sowerby - Coloured figures of English fungi or mushrooms - Cordyceps militaris

Love of nature will never die.

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