Aleochara bipustulata (Linnaeus, 1760)
POLYPHAGA Emery, 1886
STAPHYLINOIDEA Latreille, 1802
ALEOCHARINAE Fleming, 1821
ALEOCHARINI Fleming, 1821
Aleochara Gravenhorst, 1802
This species is widespread throughout Europe from the northern Mediterranean borders north to the UK and the far north of Fennoscandia, it is known to be generally common from lowlands to the upper tree line in mountain regions but many older records need to be confirmed as European workers did not recognize the distinction between the present species and the closely similar A. verna Say, 1836 until this was explained by Lohse (1986), similarly the wider Palaearctic distribution remains unclear but it is known to be widespread and to extend into Northern India. The species has long been known from North America as populations were imported during the 20th century for the biological control of various crop pests, most notably the cabbage root fly (Delia radicum L.), but recent work has shown that these belong to two similar species, A. verna and A. bilineata Gyllenhal, 1810, and it is now doubtful whether the present species has ever been present. In the UK it is generally common throughout England and Wales, though less so in the West Country, and sporadic and generally rare further north to the Scottish Highlands and in Northern Ireland. Adults are present year-round; they are active over a long season from early spring with most records between June and August. They occur in most not too wet habitats and are associated with all kinds of decaying organic matter; most frequently among sheep, horse and cattle dung and commonly in compost and among carrion and decaying vegetation but they may be found in a wide range of situations such as decaying fungi, bird nests and canine droppings. Adults feeding habits are poorly understood, they were said to predate diptera eggs but this is yet to be investigated and under laboratory conditions they have been observed consuming their own eggs and predating early instar diptera larvae. Larvae are known to parasitize a range of diptera pupae, entering as first instars and developing and pupating within, the entire life-cycle takes about one month and in northern Europe there are three generation each year. Adults may be sampled from dung or by sieving organic material, they fly over dung pasture in warm weather and can be attracted by disturbing crusted dung pats, through the winter they are often present in flood refuse and tussock samples and they sometimes occur among extraction samples of decaying vegetation.
2.0-5.0 mm, most specimens lie towards the larger end of this range. Elongate and rather narrow bodied, entirely shiny black with a large pale red spot from the suture at the base of each elytron, this may extend along the base to the posterior angles, it is generally diffuse and weakly defined and will only occasionally have sharp margins. Head transverse with weakly convex eyes and long rounded temples, surface evenly convex and finely punctured and pubescent, penultimate maxillary palpomere long and expanded towards the apex, terminal segment diminutive. Antennae with three basal segments elongate and more-or-less equal in length, the fourth quadrate or slightly transverse and five to ten strongly transverse, terminal segment long and narrowed to a rounded apex. Pronotum broadest behind the middle and curved laterally to rounded angles, apical margin straight, basal margin broadly rounded, surface evenly convex, with a longitudinal series of setiferous punctures either side of the middle, otherwise very finely punctured and pubescent, the pubescence mostly directed obliquely backwards from the centreline. From the lateral aspect the metepisternum extends beyond the elytral apex and is gradually broadened from the base. Elytra transverse and only slightly wider than the pronotum, with rounded shoulders and almost straight lateral margins, apical margin sinuate, surface with small crescent-shaped punctures and oblique pale pubescence throughout. Abdomen strongly bordered, all tergites finely punctured and pubescent throughout and lacking microsculpture, the four basal tergites impressed across the base. Legs long and slender, all tibiae with short stiff setae along the outer margins, middle and hind tibiae with a short but distinct apical spur. Tarsi 5-segmented, the hind tarsi at most as long as the tibiae and with the basal segment shorter than the next two.