Cartodere constricta (Gyllenhal, 1827)
Native to the Western Palaearctic region, this tiny mould-feeder has been transported widely with foodstuffs etc., and is now established throughout the world. The species occurs in the wild throughout Europe to the far north of Fennoscandia, and is known from most of the Mediterranean and Atlantic islands as well as across North Africa. It tends to be generally scarce throughout this range but is usually abundant where it occurs. In the UK it occurs very locally across southern and central England and Wales, and there are a few scattered records further north. The natural habitat is among decaying vegetation or under bark etc. where the humidity is sufficiently high to support the moulds, upon which it feeds, but these conditions are common among stored foods and other plant materials and so under artificial conditions it might occur anywhere and at any time. In the wild, adults have been recorded throughout the year; they are active from April until October and peak in abundance during May and June. They may be found by taking samples of damp bark or vegetation for sieving or extraction, and while the larvae are strongly photophobic, the nocturnal adults fly well and sometimes come to light. Under artificial conditions they may reproduce at any time and females deposit single eggs among suitable substrate. Larvae emerge after three days and become fully grown after about a week, they pupate within grains or among detritus, and adults emerge about five days later. This may be prolonged if the habitat is disturbed, and then both adults and larvae will rapidly disperse and continue developing elsewhere. The species is more a nuisance than a serious pest, although they are known to transport the phoretic mite Tarsomenus ascitus Delfinado, 1976, which is sometimes a serious pest of stored mushrooms. Adults are relatively easily controlled by reducing the relative humidity below 20%. The most common host materials is probably various grains or stored plant material but adults have been found among a wide range of products including dried fruits, and as such have been found wherever these are stored, including restaurants and domestic larders etc.
Cartodere constricta 1
Cartodere constricta 2
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm
1.2-1.8 mm. Elongate with a narrow forebody and broadly-oval elytra, glabrous and entirely reddish-brown, usually with the head and pronotum darker than the elytra. Head quadrate with temples and cheeks about as long as the convex and protruding eyes, surface with a median longitudinal impression and a sharp ridge inside each eye, frontoclypeal suture obvious, labrum weakly curved anteriorly, almost truncate. Antennae 11-segmented with a 2-segmented club; segment 10 quadrate and segment 11 elongate and asymmetric. Pronotum quadrate or slightly elongate, strongly constricted behind the middle and widened to rounded anterior angles and perpendicular posterior angles, lateral margins weakly denticulate, basal margin straight, apical margin curved, surface roughly sculptured and punctured, with two fine keels that converge towards the base. Elytra smoothly rounded or weakly constricted about the middle, apical margins separately rounded, striae regularly and strongly punctured, interstices 3, 5 and 7 raised from the base to well beyond the middle. Femora broad and simple, tibiae weakly broadened from the base and without obvious apical spurs. Tarsi with 3 simple segments, the terminal segment longer than the others combined. Claws smooth and not, or only very weakly, toothed at the base. Easily identified by the two segmented antennal club and the form of the pronotum.