Carpophilus dimidiatus (Fabricius, 1792)

Probably native to Old World tropical regions, this species is now established and widespread in tropical and sub-tropical regions worldwide and is regularly imported with foodstuffs to temperate regions where it often becomes temporarily established. In Europe it is established in warmer southern regions from Portugal to Ukraine, including all the Mediterranean islands, but further north, including the UK, it is exclusively synanthropic. In the wild the species develops on over-ripe fruit or at sap runs on injured trees, but it is very versatile and during dispersal will infest any fermenting material. The species has been recorded from a very wide range of products e.g. grains, rice, pineapple, oilseed, spices, honey and fruits etc. but it depends on a fairly high moisture content and generally occurs on bulk products that have been insufficiently dried or products that have been unpacked and stored in shops or food outlets. In warmer climates the species can successfully develop in humidities in equilibrium with the natural environment e.g. in South East Asia it is sometimes a serious pest of stored rice, but as a pest it is probably most detrimental to fruit crops as it is known to spread bacteria and yeasts as well as attacking the crops directly, but in cooler climates they rely on artificial moisture. Adults are active by day and night, they are strongly attracted to volatiles from fermenting fruits and grains and can fly up to 2 miles to find suitable host material, they otherwise spend most of their time hidden among host material, often alongside their larvae. Mating occurs at any time as long as the humidity is high, and while the adults lifespan is usually four or five months, they may live for more than a year if conditions become unfavourable. Females are very fecund and each may produce more than two hundred eggs, these are laid singly on the surface of host material over a long season. Under good conditions larvae emerge after a few days and complete their development within a week or two, following a prepupal stage which may last up to a week they pupate, in the wild this occurs in the soil but in artificial conditions among the host material. Thus the cycle from egg to adult takes between 12 and 42 days, depending on conditions, and there are usually several generations each year in the wild. If the temperature falls during development both larvae and pupae are capable of entering a prolonged inactive stage in the soil, similarly adults will enter the soil to overwinter or become inactive during unfavourable conditions. Both larvae and adults feed externally among host material, they are easily spotted but both stages are agile and will move and hide quickly if disturbed or suddenly exposed to light.