Insect of the Month

Confused Flour Beetle (Tribolium confusum)

This insect occurs in all life stages in warm buildings, throughout the year with two or three generations occurring each year. Females mate within one day of emerging from the pupa. Five to sixty eggs are deposited near a food site. Larvae will molt 5 or 6 times before pupating.

Both adults and larvae can feed on a wide variety of stored foods including cereals, candy, flour, fishmeal, noodles, dried spices, nuts, dead animal carcasses (drier stages), and pet foods. The larval stage prefers to hide in dark areas where food is stored, including processed and packaged foods, or in cracks and crevices where waste food has accumulated. The use of pheromone traps and inspections can determine the location and degree of infestation.

Agserv Confused Flour Beetle Insect of the Month

What do confused flour beetles look like?

Adults: These small beetles are reddish brown, and about 3.5 mm (0.15 inches) long. Confused flour beetles can be differentiated for red flour beetles by the last four segments of the antennae.
They are gradually enlarged towards the tip. On Red Flour Beetles, the last three segments of the antennae are abruptly enlarged to form a club. Adults of this species do not fly.

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 confused flour beetle life cycle?

Female confused flour beetles will deposit 200-500 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.

Damage and 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.

Fun Facts

Commonly confused with the red flour beetle (Tribolium castaneum), black flour beetle (Tribolium madens), Americanblack flour beetle (Tribolium audax), broadhorned flour beetle (Gnatocerus cornutus), and longheaded flour beetle (Latheticus oryzae).

Other common names include American flour beetle, brown flour beetle, rice flour beetle, and small flour beetle.

Confused flour beetles do not fly, but their cousins the red flour beetle (Tribolium castaneum) do.

The pheromone that attracts confused flour beetle also attracts similar species including:

  • Red flour beetle (Tribolium castaneum)

  • American black flour beetle (Tribolium audax)

  • Destructive flour beetle (Tribolium destructor)

  • Kashmir flour beetle (Tribolium freeman)

  • Black flour beetle (Tribolium madens)

Recommended monitoring systems for the Warehouse beetle are: