Uninvited guests in the nest

Having recently described the unexpected discovery of an occupied song thrush nest and the subsequent successful fledging of the chicks, being a bug-nerd at heart, I felt the need to have a closer look at the nest itself once it was no longer in use to see if any small invertebrates lay within... However, this isn't just random nosiness - there are many parasites that live in the nests of birds and mammals, and it's also the type of place where overlooked species may be found - after all, not that many people are likely to check. So, white tray in hand I began to sift...

The first species to popout was a barklouse or psocid (Psocoptera). This group contains many small species that are associated with bark, dry plant material and so on. I won't go into too much detail here, but the specimen was about 1.5 - 2mm long, variably brown with yellow and brown markings on the head, and the wings held like a shallow roof over the abdomen. Helpfully (as these tiny creatures can be tricky), the forewings also had a pattern of spots that indicated the genus Ectopsocus. As it happens, this pattern is quite strongly diagnostic and as you can see below, the spots are at the end of the wing veins and extend along them so are about twice as long as wide. This provides an identification as E. petersi - an interesting find as it is probably under-recorded, having previously been placed in the 'E. briggsi' group of similar species. However, if any psocid specialists are aware of further taxonomic changes, please do let me know.

Forewing of Ectopsocus petersi

The second species was about the same size (1.5 - 2mm), but quite different in structure - as well as the prominent bristles, it also had a relatively large ventral spring joined to the rear of the abdomen - clearly a springtail (Collembola).The blue-grey colour, which I admit was clearer in the specimen than the photos below), and other features of the ocelli, bristles and spring, plus a dark spot between the antennal bases, suggest that it is Entomobrya lanuginosa (E. myrmecophilus is associated with ants, rare and with longer bristles, while Willowsia have leaf-shaped scales rather than the covering of bristles). This is usually coastal, but inland sites are known, and a bird nest seems perfectly reasonable for a species that can be found in dry, sheltered locations.

Entomobrya lanuginosa

Close-up of Entomobrya lanuginosa

So, an urge to investigate, and a bit of work, turned up a couple of unexpected species. Possibly not as immediately engaging as nestlings becoming fledgelings (though, my bug-nerdiness means I do like them pretty much equally), but as always, species records are valuable, especially for under-recorded taxa.

References

Hopkin, S.P. (2007). A Key to the Collembola (Springtails) of Britain and Ireland. FSC, Shrewsbury. The current standard work for UK species - excellent.
New, T.R. (2005). Psocids: Psocoptera (booklice and barklice) (2nd ed.). Handbooks for the Identification of British Insects 1(7): i-iv, 1-146. Also the current standard work for UK species - also excellent.

Bark at the Moon - small invertebrates of timber (Part 4)

After yesterday's brief journey off-topic (sometimes it just has to be done), I'm back to the tiny invertebrates found in our firewood store. As promised, I've started looking at the sub-2mm critters I must say are proving tricky. This is not because of their small size as such - after all, I have microscopes - but because they include taxa which are relatively unfamiliar, not only to me, but given the lack of literature covering some of them, to entomologists more broadly. There are also difficulties associated with handling them without damage (tiiiiny tweezers, small brushes) and storing them without some of the soft-bodied organisms shrivelling to almost nothing. This has as much to do with my lack of curatorial expertise with such species as anything else. However, there is an up-side; these issues probably mean there are some under-recorded species among the bark and dead-wood (saproxylic) invertebrate community and hence some interesting records if I can make species-level determinations. First up, another barklouse or 'psocid'.

A head-on view of a barklouse. The tiny size is highlighted by using the individual lenses (ommatidia) of the eyes as a rough idea of scale.

Although it can't be seen in the photo above (due to the specimen having shrivelled I think - it's still there but very faint), there is a diagnostic anchor-shaped mark on the 'face'. The wings are reduced to tiny buds and the abdomen has several rows of dots, still visible and appearing as round 'bumps' here, though their bumpiness is a bit of an optical illusion. This is the widespread Cerobasis guestfalica which has been spread internationally through commerce such as the timber trade. Almost all specimens found are females (males occur very very rarely) which means most poulations are entirely parthenogenetic i.e. they reproduce without fertilisation by a male (New, 2005). Moving back into my comfort zone - beetles - I managed to find a single specimen of a 1.6mm bark beetle.

Note the elongate shape, rounded antennal segments and longitudinal lines on the elytra and pronotum.

A close-up of the pronotum. The hind (left) angles have a tiny tooth and there are two slightly raised lines on each side of the pronotum - the inner one is quite clear, the outer one less so, though it can be seen as a broken bright line.

This beetle is in the family Laemophloeidae - not a group I am very familiar with - and to identify it, I needed to go back to Joy (1976). The features above did however allow identification as Cryptolestes duplicatus, a species which is probably predatory and/or parasitic on the larvae of other beetles. This species has a scattered, localised distribution in south and south-east England; not rare as such but not common either, and I suspect under-recorded (as well as having seen some significant taxonomic changes which have moved it from the genus Laemophloeus within the family Cucujidae), so quite a good find. Feeling bold, I thought I'd move onto something really small - a mite (so, an arachnid rather than an insect).

A mite showing the hard surface with a few long hairs (and some bits of plant material stuck to it!), but no velvety covering as seen in the more familiar 'spider mites'.

For now, I'm not going to try to identify this - I don't have much literature covering the mites, though I do think it is in the family Acaridae, based on its overall form. However, if I feel keen I might try later, in which case an update will appear here.

So, what next for the 'Bark at the Moon' series? Well, I still have some specimens to identify and I intend to continue collecting, so although posts in this series may slow down a bit, I strongly suspect there are more to come. After all, how else to investigate these under-recorded groups..?

References

Joy, N.H. (1976). A Practical Handbook of British Beetles (2 vols.). Classey, Faringdon. (This is the resized reprint of the original 1932 classic work). A CD-ROM is also available.
New, T.R. (2005). Psocids. Psocoptera (Booklice and Barklice). RES Handbooks for the Identification of British Insects 1(7): 1-146.

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.