Dermestid larvae are usually elongate and very hairy, from above a series of transverse, well sclerotised and dark tergites are usually obvious. They can move rapidly and are surprisingly difficult to catch alive although they may be attracted to traps containing felt pads impregnated with with sardine oil (etc.) and placed on the floor. They have well developed legs with single claws and unsegmented processes (urogomphi) on the ninth abdominal segment. Some species possess hastisetae- spear shaped segmented setae unique to dermestids- which may form tufts on the posterior abdominal tergites. These are readily shed and dermestid larvae are known to produce allergic skin reactions, rhinitis and asthma.
Dermestes ater larva
Dermestids are small to medium sized beetles, 1-12mm, elongate (Dermestes, Reesa) or broad oval (Attagenus, Trogoderma) to almost circular (Anthrenus) and mostly drab coloured, various shades of brown or black although several species are distinctly marked. The upper surface is usually densely or moderately densely pubescent or covered with scales and these may form distinct patterns. Head to some extent deflexed and usually with a single median ocellus, notably absent in Dermestes spp. Antennae 5-11 segmented, apical segment(s) generally form a club and are sometimes highly modified. With the exception of Thorictodes the pronotum is transverse, narrowed anteriorly and usually with acute hind angles, the basal margin is strongly sinuate - a character used by Joy to isolate them family. The prosternum is generally excavate or distinctly grooved laterally (the hypomera) to accomodate the antennae. The elytra are antire and, with the exception of Thylodrias, completely covers the abdomen, without striae and generally with obvious random puncturation. Hind wings usually present and most species fly readily. Five abdominal sternites are visible and these are pubescent to some extent and somtimes bear tufts of setae, the pattern of which may be useful in specific determination. Like the antennae, the legs can be retracted into ventral grooves so that when alarmed the beetle can appear smooth and continous in outline. Tarsi always 5-5-5.
Thylodriadinae
Contains a single holarctic species, Thylodrias contractus Motschulsky, a very distinctive beetle - its common name being the 'Odd beetle' - for many years placed in the Cantharidae. Adults possess a single median ocellus and on discovery of the above its dermistid placing became obvious. Male 2-3mm. with widely diverging elytra, light brown or testaceous with pale pubescence. Legs long, especially tibiae. Antennae characteristic, apparently 10 segmented and with 4 apical segments elongate, longer than hand and pronotum combined. Female 2-5mm. Larviform, without elytra or wings, light or dark brown and entirely pubescent. Antennae 9 segmented and shorter than head and pronotum, apical 3 segments elongate. Synanthropic and only rarely imported. Hinton (1945) quotes museum specimens and dried flies as a food source and larvae causing damage to silk clothing
Thorictinae
Our single species, Thorictodes heydeni Reitter, is only rarely imported on stored animal and vegetqable products. A small (under 2mm.) shining reddish-brown species, elongate with rounded pronotum which is broadest in front of middle - an exception to the dermestid form. Antennae short, basal segment large and with a 3 segmented club.
Dermestinae Hide Beetles
Includes a single genus, Dermestes, of which ten species are listed. They are medium to large beetles, 5.5-12mm, characteristically shaped and either patterned with pubescence (eg D.lardarius L.) or entirely drab, brown or black (eg D.peruvianus Laporte), without a median ocellus and with 11 segmented antennae terminating in a large 3 segmented club in both sexes. Some species are entirely synanthropic and not found in the wild eg D.carnivorus Fab. or D.leechi Kalik, while others are only rarely found in the wild eg D.frischii Kugelann or D.maculatus De Geer. Some occur in both habitats eg D.lardarius L. or D.murinus L. Hide beetles require animal derived proteins for full development (Peacock), they are carnivores as well as predators and may be cannibalistic both as larvae and adults. In the wild they feed on a range of materials; they are common in birds' nests and sometimes in large numbers; the larvae of D.lardarius (and other Dermestes spp) if present in sufficient numbers will attack and kill ducklings, young pigeons and chickens (Hinton, 1945). They will consume dead insects, dead mammals and birds, feathers, honey and pollen and no doubt other materials within bees' and wasps' nests, bones and remains of carcasses including fish. Under artificial conditions they turn their attention to stored products; they have been recorded attacking leather and fur, bones, horn, feathers and glue etc etc. Much damage may be done by the faeces and cast skins produced by infestations and mature larvae may damage materials they do not use as food by their habit of boring into compact material to construct a pupal chamber, they have been recorded boring into cork, books, cardboard, plastics and wood, plaster, asbestos, woolen and cotton materials and stored tobacco. Mature larvae of D.lardarius and D.peruvarius can bore into lead easily and into tin with difficulty (Hinton, 1945). Both are common in domestic situations during the warmer months.
Of our ten species of Dermestes, D.leechi Kalik and D.carnivorus Fab. are only rarely introduced. D.frischii Kugelmann is regularly imported in animal products and sometimes found outside. D.maculatus De Geer (the Hide beetle) is a resident introduction found in animal products and occasionally outside in carrion. D.haemorrhoidalis Kuster and D.ater De Geer are both common in domestic dwellings.
Attageninae Carpet Beetles
2.3-6mm. Includes 7 species of Attagenus. With the exception of A.pellis (L.) the two spotted carpet beetle, our species occur as regular or rare introductions. The distinctive A.pellis may be found outside in the spring and early summer feeding on nectar and pollen of a wide range of flowers eg Crataegus and Spiraea. Larvae have been found in the nests of birds and bees. In both commercial and domestic premises they are pests of wool, fur and foodstuffs eg cereals. Adults of the genus are distinct in possessing a median ocellus and having the first segment of the hind tarsi half, or less than half, as long as the second.
Megatominae
11 species included within 7 genera are listed as British. All species possess a median ocellus, 9-11 segmented antennae with a 2-8 segmented club and have the first segment of the hind tarsi at least as long as the second. They are all pubescent, or have patches of scale-like pubescent dorsally. 5 species of Trogoderma (1.7-5mm) are synanthropic introductions or have been temporarily resident. T.angustum (Solier) is a recent introduction (Shaw, 1999). Reesa vespulae (Milliron), first recorded in 1977 is thus far a pest of museum collections although there have been a few records from the wild. Globicornis nigripes (Fab.), 2.3-3mm, is an endangered southern English species, adults occur in the summer among grass and foliage. Our single species of Megastoma is featured. Anthrenocerus australis (Hope) the Australian Carpet beetle is a resident introduction only infrequently encountered in domestic and industrial premises on a wide range of products. Orphinus fulvipes (Guerin-Meneville) is a rare introduction imported on a range of foodstuffs including nuts, ginger, cocoa beans and rice. Ctesias serra (Fab.) is a widely distributed species inhabiting old trees, adults occur from May to August under bark.
Anthreninae
Includes 9 spp. of Anthrenus, commonly referred to as Carpet or Museum beetles. They are distinctive species which cannot be mistaken for any other. Adults may be found indoors crawling on walls or at windows, and outside on flowers where they feed on nectar and pollen. The larvae of most species cause damage to materials of animal origin eg leather, wool and fur, they will also damage synthetic materials and vegetables if these are impregnated with animal products. A.fuscus Olivier and A.museorum (L.) occur almost entirely in the wild, the larvae live on dead insects and are often found among detritus in or around spiders' webs. A.verbasci (L.) is a common domestic pest of southern England, as well as infesting a very wide range of products it is notorious for its habit of destroying collections of dried insects. A.sarnicus Mroczkowski has recently become established as a museum pest in the London area. Our other species are recorded only occasionally with imports.
Trinodinae
Our single species, Trinodes hirtus (Fab.), is a widely distributed 'English' insect associated with wooded habitats, more especially Oak. Adults occur from May to August either on flowers and foliage or near accumulations of dead insects among spiders' webs under bark or in tree crevices. A small species, 3mm or so, broad-oval and widest behind middle, grey with long black pubescence. Without or with a very small median ocellus and pronotum with basal sublateral carina.
With the exception of Trogoderma all species listed as British are keyed by Peacock (1993). A great deal of information regarding the synanthropic species is given by Hinton (1945)
Reference
Shaw, M.R. 1999.Trogoderma angustum, a museum and herbarian pest new to Britain. Entomolgists Gazette. 50:99-102
Dermestes ater
Dermestes haemorrhoidalis
Dermestes lardarius
Megatoma undata
Megatoma undata
Megatoma undata
Anthrenus fuscus
Anthrenus fuscus
Anthrenus verbasci
Anthrenus verbasci