Dermestes ater De Geer, 1774

Although not established in the UK this species is regularly imported (Peacock) and may occur among a wide range of materials. On the continent it has been established at various times eg in domestic dwellings in Finland from 1900-1939, especially those hosting the German Cockroach, and in Germany (Various records in Hinton). The species is of worldwide distribution and for the most part strongly syanthropic and so may be found among all sorts of imported materials although it is thought to feed and develop primarily on the dead bodies of insects among these. Recorded hosts include (Hinton, Ibid) dried cockroaches and carcasses of dead birds and animals (Hawaii), dried fish, hides and leather goods, cheese, dead adults and pupae of silkworms and somtimes cocoons as well as silken goods, copra, rotten nuts and dried mushrroms etc. In tropical conditions it occurs in the wild on a range of carcasses (Peacock)
UK records are erratic and include imports from Australia and oriental regions. Data from rearing the species from eggs are given by Hinton; briefly, with specimens reared on dried cockroaches (in Hawaii) the larval period lasted between 28 and 41 days while the pupal period was in all (6) cases 9 days. There are 7 instars. The larvae are not cannibalistic and do not consume their cast skins. The last larval skin is shed after pupation (but see below). Lack of water will retard larval development. When disturbed both larvae and adults will feign death.

Included on the Watford list on the basis of specimens reared from eggs and larvae found among samples of live crickets pruchased from a local petshop. Between May and July four samples of crickets were found to host the beetle. A further sample rchased on 3rd July and examined thoroughly and no larvae were present. As purchased the sample contained numerous crickets at all stages of development, a piece of 'egg tray' and a layer of cast cricket skins. The sample was left in daylight at ambient temperature and the first tiny larvae were seen on 7th July. Five larvae were found and these developed rapidly within a deep litter of cast cricket skins and without any source of water. Pupation occurred around the beginning of August but was at first difficult to detect as the pupae remain with the last larval skin. The first adult emerged on the 8th or 9th of August and several over the following week.

Larvae from another batch were tempted with alternative foodstuffs but in the presence of cast cricket skins would feed on nothing else. Isolated for a few days in a small plastic container and without any food, a single larvae was observed to feed on a small piece of sliced ham, only a tiny amount of food was taken and the rest ignored. Other foods were offered but ignored altogether eg bread, cheese, digestive and bourbon biscuits, and boiled egg white. One specimen, starved for 10 days, ignored wholemeal bread but commenced feeding on cricket skin immediately this was offered.

Two species of Dermestes are superficially very similar to D.ater and to achieve a certain identification the first (visible) abdominal sternite will need to be examined; in ater the impressed lines parallel to the lateral margin are angled inwards towards the base so that when they terminate next to the metasternal hind margin they are some distance from the edge. In D.peruvianus and D.haemorrhoidalis these lines are parallel to the side margin throughout their length. This character is visible from the side without dismounting the specimen so long as the legs do not obscure it. The undersurface pubescence in ater is unique; all abdominal sternites have a symetrical pattern of light and dark pubescence, in most lights the dark pubescence is not, or is only barely, visible and so these areas may appear glabrous next to the lighter (grey) pubescence.

7-9mm. Entirely dark brown but for lighter antennae. Upper surface finely and randomly punctate. Head sparsely pubescent, convex and without impressions, eyes large and hemispherical, mandibles protruding. Antennae 11 segmented, first segment large and curved on inner side, 2-5 quadrate, 6-8 transverse and 9-11 forming a club. Pronotum convex, broadest at middle and narrowed to front margin, with a weak fovea either side of middle near base, hind margin sinuate. Entire surface with backwardly recumbent fine golden pubescence sometimes with a few spots of golden setae (Peacock). Elytra parallel, with a series of weakly raised ridges, the inner ones diverging near base. Pubescence as on pronotum, not forming any pattern. Cuticle uniformly dark. Tarsi 5-5-5, first segment of mid and hind tarsi generally a little shorter than second, at most subequal.