Bark at the Moon - small invertebrates of timber (Part 1)

OK, it's Halloween and I seriously thought about posting something truly ghoulish, but in the end only came up with a slightly cheesy title... mainly because I spent part of the day identifying some small (2-3mm) specimens that I collected from our firewood store. There were some smaller specimens but I have yet to work through them (they may appear here soon); however, I thought it might be interesting to have a look at some of the invertebrates associated with stored timber, especially as they can be brought to our homes by hiding under bark and in crevices when forewood is brought in from elsewhere. Our firewood is all fairly local, so there is unlikely to be abything exotic, but given their small size, it is possible than some of the organisms found might represent under-recorded taxa.

The first of these is a barklouse which as its name suggests is associated with bark. These were numerous and as far as I can tell all those I collected were female and at least some were gravid (contained eggs).

Side view of the barklouse.

Dorsal view of the head showing features including the yellow patches at the inner rear edges of the eyes.

The 'laciniae', end segments of the maxillae (mouthparts) which have a distinctive shape (a 'pie-crust' edge) and are hardened for curtting and manipulating food.

 

The forewing showing hairs, vein/cell pattern and pale larks on an otherwise brownish wing (the other colours are interference patterns and reflections).

These features combine to provide an identification as Epicaecilius pilipennis. This species was first recorded in Britain in the late 1990s but has since been shown to be widespread (whether or not it is common) with specimens from Scotland to the south coast and various locations in between. It is in the family Caeciliusidae within which it is unusual in being associated with tree trunks rather than foliage (New, 2005).

It certainly seems locally abundant, but this is a species with a British distribution which is not well understood. This shows the value of looking in places such as household timber stores and sheds where overlooked taxa may well be found. More about our firewood inhabitants soon...

Reference


New, T.R. (2005). Psocids. Psocoptera (Booklice and Barklice). RES Handbooks for the Identification of British Insects 1(7): 1-146.