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Strange beetle larva

Posted: Tuesday 3 January 2012
by Richard Jones

Apparently, gardeners sometimes have a look around to see what other gardeners are growing in their gardens [...] but I have a look to see what other wildlife they are finding.


Drilus larva

Apparently, gardeners sometimes have a look around to see what other gardeners are growing in their gardens. I am guilty of the same diversions, but I have a look to see what other wildlife they are finding. Unashamedly, I can give a big plug for the iSpot website run by Open University. It was here that I came across this strange beast (pictured above) photographed and posted a short while ago by June Somerville.

It is the larva of a small black and brown beetle called Drilus flavescens. No English name, sadly. The beetle is pretty scarce, in that it is more or less limited to dry chalky and sandy places in south-east England, but it regularly turns up on chalk downlands and the small males fly actively in hot weather.

The larva on the other hand, must rank as one of our rarest insects, or at least one of the most rarely seen. Obviously it must be as frequent as the adults, but it leads a singularly secretive life. It’s a bit of a mystery why the larva should be so scarce. It eats snails, and lives in the grass root thatch. According to the entomologist who first worked out its life history, back in 1903, Drilus is easy to rear. It eats a wide variety of snail species including the common banded hedge snails Cepaea nemoralis and C. hortensis.

The female Drilus is also very rare. She is not a bit beetle-like and looks like the larva, but lacks the feathery fern-frond appendages. Being wingless, she cannot fly off to found new colonies, but can only crawl.

It is no wonder that June was unable to identify her find; no regular garden wildlife books (or even popular insect guides) would ever have a picture of so unusual a beast in them. What a fantastic thing to uncover in the garden, under camellia and ceanothus leaves.



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Luke Arnos 11/01/2012 at 15:02

This is really weird. What are the tufty bits along its body for?

Richard Jones 12/01/2012 at 08:10

Reply to Luke Arnos
The feathery fronds are a bit of a mystery. We know hardly anything about these beetles' life histories. My only guess is that they help prevent the larva getting covered in snail mucous when they attack their prey.