Warehouse beetle
Trogoderma variabile Ballion

Order: Coleoptera
Family: Dermestidae
Acronym: TVA

Ecology

The warehouse beetle is worldwide in distribution. It is thought to have originated in Central Asia. In Canada, it is distributed from coast to coast where it is found in flour and feed mills, processing plants, feed warehouses, dried milk factories and in stored grain. The warehouse beetle is the second most important Trogoderma species world wide. It feeds on a variety of stored seeds, legumes, nuts and high-protein content products. It prefers to feed on animal feeds, barley, wheat and pollen. It is a known pest of Alfalfa leaf cutter bee nests, an important crop pollinator. The warehouse beetle looks very similar to other Trogoderma species.

Damage

The warehouse beetle is a generalist feeder and does not create any distinctive damage. The larva feeding causes damage to the commodity. It feeds on stored seeds, legumes, nuts and processed foods. The larva damages seeds by eating all parts of the kernel except the shell. It can chew holes in thick plastic. The larva can infest bagged grain and processed packaged foods. A sign of infestation is contamination with cast larval skins.

Life history

The adult is bicolourous or two-coloured. It is mostly dark brown with three distinctive wavy lighter brown bands on the elytra. It is covered in fine hairs and it is shaped like an elongate oval. It is 2 – 4.6 mm long. Adult longevity is 10-60 days. The adult can fly. It does not feed on the commodity.

Optimal breeding condition temperatures range from 17°C to 37°C. The adults mate immediately after pupation. The female is larger than the male. She lays her eggs singly in the food source. She will lay up to 80 eggs under optimal conditions.

The larva is oval shaped and covered in hairs. It is whitish yellow when young and reddish brown when mature. It has tufts of dense hairs located on the last abdominal segments. The optimum temperature for development is 30°C, 70% relative humidity. The shortest development time is 30 days with an average of 45 days. The larva moults many times during development. Under adverse conditions, it will moult even more. It can enter a state of diapause if the environment is unsuitable for development. The larva pupates in the last larval skin.

Control

Controlling insect infestations

Images

Adult: Warehouse beetle

Larva: Warehouse beetle