Trogoderma variabile

Adult warehouse beetles average about 3.2 mm (0.13 in) in length and are some shade of reddish-brown, dark brown or blackish-brown. The larvae are cream coloured or some darker shade of brown, and average 6 mm (0.24 in) in length when fully grown; they have long bristles at the tip of the abdomen.[1]

This beetle may have originated in Central Asia, but is now widely distributed, being found in Russia, China, parts of the Middle East, Europe, Central America, North America and Oceania.[1][2][3] It is an economic pest in a range of dry goods including animal foods, wheat and barley kernels, wholemeal flour, corn meal, oat meal, noodles and other cereal-based foodstuffs. It also infests animal detritus, fish meal, spices, nuts, cocoa and sugar products.[1] In the indoor environment it occurs in warehouses, granaries, food stores and dwellings, and outdoors in Russia, it has been found in bee nests.[4]

Eggs are laid in suitable dry materials, and if kept in the temperature range 20 to 38 °C (68 to 100 °F), hatch in about a week. There are normally six instars, and some mature larvae enter an active diapause, especially in cooler habitats, and may remain in the larval state for two years.[1] Non-diapausing larvae pupate near the surface of the foodstuff about seven weeks after the eggs were laid; the pupation period lasts about four days, and the new adults rest for two to seven days before emerging from the last larval skin.[1] Longevity for males is nine days at 40 °C (104 °F) and several weeks under cooler conditions. Females also live longer at lower temperatures.[1]