Carpophilus marginellus Motschulsky, 1858
Native to southeast Asia and spread with the trade in foodstuffs, this species is now more-or less cosmopolitan in distribution; it occurs in artificial conditions worldwide but has also become established in the wild, albeit sporadically, throughout the tropics and in many temperate regions, it is known from the wild in most European countries and seems generally to be increasing in abundance. It has long been recognized as an imported pest species in the UK but it was first recorded in the wild during the 1950s when it was thought that such records were the result of specimens originating in artificial conditions, but since that time it has been widely recorded across southern England from a variety of habitats, it has become locally common in many areas, and there is now no doubt that it is established in the wild. As a pest species it is associated with a wide range of fresh and stored products including nuts, cocoa bean, copra and dried coconut, pasta, spices, rice, various peas, soybean, maize, wheat and wheat flour, and a very wide range of dried fruits, it rarely occurs in domestic premises but occasionally occur in large numbers in mills, grain elevators and nut-processing plants etc, where it may cause serious commercial damage. In warmer climates they often attack fresh fruit at all stages of development, processing and storage e.g. they have become widely established in peach and nectarine orchards in Australia and are a general pest of developing pineapples throughout the tropics. In temperate regions they are associated with decaying organic matter in a wide range of situations; adults have been recorded from salt marsh vegetation, compost, silage, straw and fungus on dead trees in woodland, parks, gardens and disturbed sites generally, but they also visit flowers, particularly blossom, and in Japan they have been studied for use as pollinators for various soft fruits. Under artificial conditions they may be continuously brooded but under natural conditions in temperate regions they are probably univoltine, with larvae developing through the summer and pupae or adults overwintering. The life cycle has been extensively studied and under artificial conditions, reared on fresh pineapple at 20°C, larvae are fully developed within about 22 days, the pupal stage occurs in the ground and lasts about 18 days and the entire cycle from egg to adult takes about 50 days, this is more rapid at higher temperatures and the cycle may be completed in about 20 days at 30°C. Wild adults may occur among decaying or, especially, fermenting organic matter in a range of situations, but they are nocturnal and may be found by searching standing or fallen timber, especially where decaying leaves etc have accumulated in hollows or cracks, they are attracted to fermenting sap and to light, and occasionally occur on walls or at windows in domestic premises as well as in restaurants etc. Adults are unlikely to become serious domestic pests because modern hygiene generally deprives them of suitable host material, but having made the transition to the wild it is likely the beetles will regularly occur inside, especially as they are strongly attracted to a wide range of both fresh and dried fruit.
2.0-3.5mm. Entirely dark chestnut-brown, usually with the margins of the pronotum and elytra paler, flattened and broadly elongate-oval, rather parallel-sided and easily recognized, at least to the genus, by the form of the antennae and the exposed apical abdominal tergites. Dorsal surface finely and quite densely punctured and pubescent throughout. Head transverse and evenly convex, without sculpture, eyes large and weakly convex, clypeus narrowed in front of the eyes to a wide and truncate labrum. Mandibles robust, curved, sharply pointed and with an internal tooth. Antennae inserted laterally in front of the eyes, 11-segmented; basal segment broad and curved internally, 2 & 3 much longer than 4-8, and 9-11 widely transverse, forming a compact club. Pronotum transverse, basal half parallel-sided and anteriorly curved to a straight and narrow apical margin, posterior angles slightly obtuse and the basal margin straight and finely bordered, surface without impressions or sculpture. Scutellum transverse and angled laterally. Elytra slightly transverse, across the base about as wide as the base of the pronotum, only weakly curved laterally and apical margins converging to the suture, without striae, the surface punctation a little finer than that on the pronotum. Visible abdominal tergites finely and densely punctured throughout. Mesosternum with a fine median longitudinal ridge, the apex of which is obscured by the rounded apical margin of the prosternal process. Metasternum with a fine oblique line from the inner margin of the meso-coxae towards the apical margin of the met-episterna. Legs short and robust, all tibiae expanded to a truncate apical margin and with well-developed apical spurs, tarsi 5-segmented; the basal segments short and lobed, and the apical segment long and slender, claws smooth and without a basal tooth.