Insect of the Month: Red Flour Beetle
The red flour beetle (Tribolium castaneum) is a common stored-product pest affecting grain, flour, and processed food products across Australia. It is primarily an issue in mills, food manufacturing, warehouses, supermarkets, and on-farm storage, rather than domestic environments.
What do Red Flour Beetles look like?
Red Flour Beetle Adults: These small beetles are reddish brown, and about 3.5 mm (0.15 inches) long. Red flour beetles can be differentiated from Confused flour beetles by the last four segments of the antennae.
On Red Flour Beetles, the last three segments of the antennae are abruptly enlarged to form a club. Confused flour beetle are gradually enlarged towards the tip. Adult Red Flour Beetles of this species fly in warmer temperatures, usually above 29°C (85°F).
Eggs: Oval, ivory in color and only visible under microscopic examination of flour products.
Larvae: The immature stage is approximately 4-5 mm (0.25 inches) long, white to yellowish in color, and wiry in appearance. The last abdominal segment ends with two prominent points.
Pupae: Pupal cases are white to yellowish in color and nearly the same size as adult beetles. The tip of the abdomen ends with two prominent points.
What is the Red Flour Beetle Life Cycle?
Female red flour beetles will deposit 200-450 eggs in food during a 1-3 year life span. Eggs hatch in 5-12 days, and the larvae can mature within 30 days in warmer months or as long as 120 days in cooler months. The life cycle of this species is shorter than the Confused Flour beetle. The reproductive rate, as a result, is usually higher as well.
Red Flour Beetle Damage & Detection
Heavy infestations of flour by this insect may cause the product to turn greyish or mold prematurely. This insect can also give a citronella-like smell and taste from its scent glands to the material infested. They are primarily pests of flour, but also feed on processed beans, nuts, spices, chocolate, and pharmaceuticals. Both adults and larvae cause damage.
Red Flour Beetle Facts
Similar species include confused flour beetle (Tribolium confusum), black flour beetle (Tribolium madens), American black flour beetle (Tribolium audax), broadhorned flour beetle (Gnatocerus cornutus), and longheaded flour beetle (Latheticus oryzae).
Other common names include rust-red flour beetle, red brown rice flour beetle, and small flour worm.
Red flour beetles initiate flight at temperatures above 20°C (68°F).
The pheromone that attracts red flour beetle also attracts similar species including:
- Confused flour beetle (Tribolium confusum)
- American black flour beetle (Tribolium audax)
- Destructive flour beetle (Tribolium destructor)
- Kashmir flour beetle (Tribolium freeman)
- Black flour beetle (Tribolium madens)
Recommended monitoring systems & treatment for the Red Flour Beetle:
- Hanging NoSurvivor Trap with PTL Multi-Species Bullet Lure (IL-408)
- Dragnet Dust
