Bark at the Moon - small invertebrates of timber (Part 3)

OK, only an hour to go before I head off to the firework display at our local pub, so apologies for any typos that get missed in the hurry...

Anyhow, as promised I've started looking at some of the tinier invertebrates found in our firewood store - by tinier I mean below 2mm but still visible (just) with the naked eye. I have quite a few still to look at, but the first is a springtail (Collembola) which despite its small size can be identified without a microscope if you have good close-up vision.

A springtail - the head is to the right and the 'spring' is out of frame to the left.

This springtail is Entomobrya albocincta and can be identified by the 'mane' of straggly hairs which also run along the dorsal surface, and the alternating dark and pale patches which give it a striped appearance. Even without a microscope, the palest mark just behind the head is clearly visible and the other mark just behind the mid-point can also be seen. This is a common and widespread species (there were plenty in our wood store) and is indeed usually associated with dead wood or found under bark (Hopkin, 2007).

As I mentioned above, I've only just started looking at the smaller residents of our wood store and I'm sure there are other sub-2mm specimens I'll be able to identify. However, along the way I found a couple of other interesting species, a little larger at 3-4mm.

An unusual creature - very flat with short wing-buds. Also note the pattern of red spots near the rear end. The overall colour and pattern provide excellent camouflage on bark and among lichen and plant material.

The 2nd and 3rd antennal segments are the same length. Note also the spines either side of the rostrum and the red eyes.

A close-up of the midline of the dorsal surface showing tiny pinkish tubercles (bumps) and other sculpturing.

This slightly odd-looking specimen is a nymph of one of the flatbugs, Aradus depressus, a true bug (Hemiptera) in the familt Aradidae. Adults develop fully sized wings and this species is often found on the damp ends of cut timber - no great surprise to find it among firewood. It is again a fairly common species and feeds on the mycelia (threads) and fruiting bodies of Polyporus and other fungi (Southwood & Leston, 1959).Moving on, I found what looked like another barklouse (psocid)...

A barklouse with short, hairy/scaly wings and long antennae. The bulging eyes suggest it is a male.

A close-up of the head - note the clear pattern of dark marks. The dense layer of silky hair-like flattened scales can be seen covering the wings and there are also larger bristles around the outer edge. The antennae have numerous small segments, each with its own small hairs.

This combination of features is quite distinctive and shows this to be a specimen of Pteroxanium kelloggi. It is usually found in leaf litter and is only rarely seen on bark or attached foliage (New, 2005), so is not usually associated with timber piles. It is the only species of the family Lepidopsocidae regularly found outdoors in Britain - there are three other species of this family known from Britain, but they are rare, casual introductions. The name of the family is also a good indicator of its form in this case - like the Lepidoptera (scaly-wings) i.e. the butterflies and moths, it is named after the dense flat scales on the forewings.

And so, we have some more species from our wood pile - it is turning out to be a local biodiversity hot-spot! It's time for the weekend to start now, but I should return soon with Part 4 of this series and hopefully more on the tinier residents.


References

Hopkin, S.P. (2007). A Key to the Collembola (Springtails) of Britain and Ireland. FSC, Shrewsbury.

New, T.R. (2005). Psocids. Psocoptera (Booklice and Barklice). RES Handbooks for the Identification of British Insects 1(7): 1-146.
Southwood, T.R.E. & Leston, D. (1959). Land & Water Bugs of the British Isles. Warne, London.