Rust red flour beetle (Tribolium castaneum)

Type of pest: Primary pest, secondary pest.

Distribution: Worldwide.

Identification: Adults are 3 – 4.5 mm flattened, parallel-sided and reddish-brown. The larva are tawny in color and 6-8 mm. The gap between eyes is 33% of the head width. The last three segments of antennae are a distinct club. The structure between the base of front legs is widest at the tip (like an axe head). The eye is divided, with the number of facets at the narrowest point 2. Larvae: elateriform.

Similar species: Gnatocerus, Latheticus, other Tribolium.

The term flour beetle is often used to describe one of two main classifications of the rust red flour beetles (Tribolium castaneum) and the confused flour beetle (Tribolium confusum). When identifying the insect the biggest distinguishing difference is their antennae shape. There are difference such as that the adult rust red flour beetle can fly (only when stressed) whereas the confused flour beetle cannot.

Life cycle: Optimal conditions are 20 days at 35-38 ºC > 70% r.h. An adult female can lay about 1,000 eggs in 400 days. Eggs are laid amongst the commodity. The larvae are mobile, external feeders. Adults are long-lived, feed on the commodity and fly.

Commodities infested: Dried material of animal and plant origin, especially cereal grain and products, oilseeds. These beetles may cause an allergic response, but are not known to spread diseases and cause no damage to structures or furniture. They can only eat damaged or milled grain and both are often introduced to a warehouse or production facility through infested flour deliveries.

Preventive measures include: keep storage and production area dry and clean, relative humidity in storage needs be maintained between 40% and 60% and ensure that packaging materials pallets etc. are clean and dry before storage.

Treatment: Controlled Atmosphere for infestation in the product
Treatment: Heat Treatment for infestation in buildings