Flour beetle

Tribolium destructor (Uyttenboogaart) adults are dark brown beetles, 4.5–5.7 mm in body length—the largest species in the genus. As in other Tribolium, the compound eyes are distinctly emarginate, narrowing to about two ommatidia at the isthmus. Larvae are typical for the genus: yellowish with clear dark bands; the head capsule and the terminal urogomphi are conspicuously darkly pigmented.

A generalist stored-product beetle, it behaves mainly as a secondary feeder on cracked kernels, milled fractions, and residues. Feeding on endosperm and germ causes comminution of grain, more fines, and reduced test weight. The bulk becomes contaminated with frass, exuviae, and insect fragments, leading to downgrade and dockage. Insect metabolism elevates temperature and moisture, creating hotspots and caking, and predisposing the mass to secondary fungal and mite proliferation. Consequences include off-odors, discoloration, and loss of palatability; in seed lots, reduced germination. Because injury is diffuse and non-diagnostic, losses are both quantitative (weight loss) and qualitative (nutritional and sanitary quality), without distinctive kernel perforation patterns.

Key signs indicating the flour beetle Tribolium destructor Uyttenboogaart in stored grain: - Unpleasant, acrid odor from infested lots—often the earliest indicator. - Presence of life stages: active adults and larvae within kernels and intergranular spaces. - Feeding damage to kernels: perforations, gnawed endosperm, and mealy residues. - Localized heating (metabolic hotspots) or elevated grain temperature from insect activity. - Accumulations of fine, floury dust and frass in handling points and along bin floors. - Grain discoloration and a dull, dusty appearance consistent with ongoing feeding.

Tribolium destructor Uyttenboogaart reproduces within stored flours and broken grain. Females perform random oviposition among the commodity. Neonate larvae emerge and feed in situ on fines and damaged kernels, producing frass. Development proceeds through several larval instars, followed by a quiescent pupal stage in the food matrix. The teneral adult ecloses, hardens, darkens, and soon mates; adults are long‑lived, iteroparous, and can generate overlapping generations. This species does not tolerate temperatures above 30°C, so survival and fecundity decline at higher temperatures.

Tribolium destructor Uyttenboogaart prefers synanthropic stored‑product sites: flour mills, bakeries, and household pantries, breeding in flour dust and cereal residues.

Broad-horned flour beetle (Gnatocerus cornutus) Longheaded flour beetle (Latheticus oryzae) Other species of the genus Tribolium