Aradidae

Flatbugs

HEMIPTERA > HETEROPTERA > PENTATOMORPHA > ARADOIDEA > Aradidae

The members of this small family, commonly known as either flatbugs or barkbugs, are primarily fungal feeders that live most of their life under the bark of decaying trees. They have a flattened body, strong legs and short antennae, which enable them to crawl into tiny crevices where they are obviously very difficult to find. Occasionally they may be seen on the surface or on wood debris on the forest floor, but unless you're specifically looking for them, encounters are likely to be very few and far between.

Although seven species have been recorded in Britain, only four are normally considered and only three of those are likely to be found in my area. There are two genera; Aneurus with two very similar species, and Aradus with five species.

Aneurus laevis is a dark reddish-brown species, about 4-5mm long with a broad, flattened body and completely membranous wings apart from the base. The forewings are fully developed, but the rear wings are greatly reduced effectively reducing the bug's ability to fly.

Aneurus avenius is extremely similar and, in truth, probably impossible to reliably distinguish from photos. However, the individual featured here is a male, confirmed by the small protruding and rounded genital segment, which does not appear to be distorting the flattened wing membrane as it does in Aneurus laevis.

Both species occur under the bark of dead, rotting trees, which are affected by fungi; the former in both broadleaved woodland and coniferous forests, and the latter more likely on native deciduous trees. They are regarded as common in England and parts of Wales, rarer further north, but are seldom recorded.

Recent distribution data suggests that Aneurus avenius is the most frequently seen and certainly the most likely of the two species to be found in Dorset (VC9) or South Hampshire (VC11).

Aradus depressus is more widely distributed and the most likely flatbug to be encountered in most areas. Unlike the two Aneurus species, the wing membrane in Aradus does not extend below the apex of the scutellum. Adults are brown with whitish, reddish and black markings, but are distinguished by the pale shoulders. It is a tad larger than the other species at 5-6mm.

They also occur in woodland but, as with Aneurus avenius, are more likely to be found on native deciduous trees. The common name Pale-shouldered Flatbug is often used to identify the species.

I've found nymphs on a couple of occasions, but have yet to see an adult.

Aradus cinnamomeus, commonly known as the Pine Flatbug, was pretty much restricted to Surrey heathland where it could occasionally be found on Scots Pine feeding on sap, rather than fungi like other flatbugs. There are very few official records, but interestingly the most recent have been from Norfolk, so it may just be that the species is not being seen or identified and recorded. It is a reddish-brown colour and grows to much the same size as the two Aneurus species.

Updated, Feb.25 (v.2)