Carpophilus hemipterus (Linnaeus, 1758)

Endemic to tropical regions but regularly imported with foodstuff to temperate areas, this species is now of more-or-less cosmopolitan distribution, it occurs in warehouses and stores throughout Europe and is known to have become widely established in the wild, mostly in farms and orchards etc. where fruits are stored but also occasionally among decaying vegetables and compost. The species is mostly synanthropic in the UK; it remains very local and scarce but is regularly recorded across Britain and occasionally from Ireland. The species is a major pest of both harvested and growing fruits in warmer regions and can destroy harvests by introducing yeasts and bacteria into developing fruits, and while a wide range of products may be attacked under artificial conditions it is usually more of a nuisance in temperate regions, especially in Europe where quality controls tend to ne stringent. Among the products attacked are any kind of fresh or dried fruit, corn, wheat, oats, nuts, rice copra and spices as well as processed foods such as bread, sugar, honey and cornmeal. Adults are both diurnal and nocturnal, they tend to be very active among stored products and while they are reluctant to fly they can migrate over several miles in only a few days in search of new host material. They are attracted to volatiles and because humidity is very important for developing larvae etc. they tend to ignore foods maintained at low humidities. Under good conditions the life-cycle can be very rapid and large populations may form, adults may live for up to a year but males usually live for about six months while females average about four months. In temperate regions there is likely to be only a single generation in the wild but in artificially-heated stores and buildings they breed continuously. Females mate and begin ovipositing soon after they emerge and continue to produce eggs through their lives; they lay single eggs on ripe or damaged fruits and larvae emerge after a day or two. Larval development depends upon humidity, from 19 days at 92% to 24 days at 66%, and the lowest moisture content needed for survival is 10%. There are usually four larval instars but as humidity decreases many enter a fifth instar. Pupation takes place underground in the wild but among host material indoors, pupal development also depends on humidity and temperature but under good conditions takes between four and sixteen days. Thus the cycle from egg to adult may be completed within twelve days at 32°C and up to 42 days at 18°C. Females may produce more than a thousand eggs over their lifetime and so the potential for increase id huge, especially as they may hibernate as larvae, pupae or adults when temperatures decrease.