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Notes on Endomychus coccineus L.
By E. E. SYMS, F.R.E.S., F.Z.S.
Among the beetles to be found in Epping Forest is one known as Endomychus
coccineus. This is a local beetle, and at first sight looks like a ladybird.
It is bright blood red in colour with a black head and antennae and has a
black spot in the centre of the thorax and two black spots on each elytron. It
measures some 5 mm. long by 3.5 mm. broad. It is to be found on old decaying
trees and has been recorded from fir, beech, hornbeam, willow and alder.
My first experience with this beetle was some years ago, when searching
in the Forest I removed the bark from a hornbeam and underneath was a
mass of these beetles. I did not count them but I should say there were 30
or 40. I thought they were hibernating, but took home a few and put them
up in a cage, expecting to see them active in the spring. The following
January I was again in the Forest and found under the bark of a dead tree
one of the false-scorpions which I took home together with a piece of bark
on which it was resting. Looking into the cage a few days later I noticed a
black object on the fungus that was growing on the bark. It looked like a
very small wood louse, but when examined with a lens was found to be the
larva of a beetle. I compared it with the drawing in Westwood's Modern
Classification of Insects, and found it to be the larva of Endomychus
coccineus. This made me examine the cage in which I had put up the beetles
the previous September. I found that they had all left the bark and were
scattered all over the cage and were dead. These beetles when found were
not hibernating but were probably feeding upon the mycelium of a fungus.
Stephens' Illustrations of British Entomology says that in 1816 at Coom-wood
they were found crowded together and were collected by the handful. I
have found the beetle several times but never in numbers. I visited the
tree from which I obtained the original larva and collected a number, these
fed up well on the leathery fungus that grows upon the outer bark of trees.
When fully grown, the larva measures some 7 mm. long and 3.5 mm. wide.
It is rather flat and black in colour and the dorsal plates overhang the sides
of the larva, and some of these plates are yellow. Whilst examining the
full-grown larvae I found one that had changed to a brown colour and was
dead, it had been killed by Chalcid parasite. This parasite was responsible
for the death of most of the larvae. Only four larvae survived and pupated,
the larval skin was not completely removed but was retained on the tail end
of the pupa. The pupae were pink and the surface covered with short
bristles; these gave it a woolly appearance.
Having seen the larvae and pupae, I wanted to see the eggs, so I
collected a few beetles and put them up. I was successful in obtaining a few.
They were spherical with a smooth shell, and were deposited on 3rd
September, on the edge of the fungus. I have never been able to find the
eggs out in the open.