Common Name: Confused Flour Beetle
Scientific Name: Tribolium confusum (duVal)
Class/Order/Family: Insecta/Coleoptera?Tenebrionidae
Metamorphosis: Complete
Introduction
The confused flour beetle apparently got its common name because of the confusion regarding its identity. It is one of the most important pests of stored products found in the home and in grocery stores. Although of African origin, it now occurs worldwide in cooler climates. In the United States, it is more abundant in the northern states.
Recognition
Adults about 1/8: (3-4 mm) long. Color reddish brown. Antennae gradually clublike, club 4-segmented. Sides of thorax almost straight, at least much more so than curved sides of red flour beetle. Adults with wings, but never observed flying. Except for antennal and thorax differences, almost identical to red flour beetle. Full-grown larva about 1/8-1/4″ (4-5 mm) long.
Hard-bodied, cylindrical, wiry in appearance. Color white but tinged yellowish. Distinguishable from larvae of somewhat similar appearance by the darken prominent, 2-pronged non-movable and unsegmented termination of last body segment (=urogomphi); the same distinction is true for red flour beetles.
Similar Groups
(1) Red flour beetles (Tribolium castaneum) with antennae abruptly clubbed, club 3-segmented.
(2) Broadhorned (Gnathocerus cornutus) and slenderhorned (G. Maxillosus) flour beetles lack antennal club, male mandibles armed with a pair of incurved horns, length about 1/8″ (4.2 mm and 3.2 mm respectively).
(3) Black (Tribolium audax) and false black (T.destructor) flour beetles black, length about 1/4″ (5-6 mm and 6-7 mm respectively).
(4) Longheaded flour beetle (Latheticus oryzae) pale yellow brown, antennae loosely clubbed with last segment smaller and/or narrower than preceding segment.
(5) Lesser mealworm (Alphitobius diaperinus) with eye almost completely divided, length about 1/4″ (5-6 mm).
(6) Yellow (Tenebrio molitor) and dark (T.obsurus) mealworms black, length about 1/2-3.4: (12-20 mm).
Biology
The confused flour beetle female deposits about 300-500 clear-white sticky eggs on or among food materials in cracks, in bags, or through the mesh of sacks containing food. The female lays 2-3 eggs per day, but lives for 2-3 years. The eggs hatch in 5-12 days into brownish-white larvae, which go through 5-18 instars (usually 7-8) and reach maturity in about 30 days under optimal conditions. The life cycle (egg to egg) can be completed in only 7 weeks, or it may require 3 months or longer. In heated storage facilities and processing plants, there are 4 or 5 generations annually.
Habits
These beetles are unable to feed on whole kernels or undamaged grain. They have been recorded attacking grains and grain products, peas, beans, shelled nuts, dried fruits, spices, milk chocolate, drugs, snuff, cayenne pepper, and herbarium, insect and other museum specimens. They have been found to infest poisoned baits. They are attracted to light even though they apparently do not fly. Although humans are not injured by it, confused flour beetles do impart a disagreeable odor and taste to the flour they infest.
Control
Follow the standard control procedures for stored product pests.