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.