Warehouse beetle

Warehouse beetle (Trogoderma variabile Ballion) adults are oval, 2.0–4.6 mm long; females are larger than males. The elytra are generally dark, with contrasting bands in shades from brown to reddish; most adults appear dark brown with three paler brown or reddish bands. Larvae are initially yellowish‑whitish and darken with age. They show the characteristic Dermestidae larval habitus, with dense setal tufts on the terminal abdominal segments.

Warm, dry, dusty stored‑product environments: flour and feed mills, processing plants, feed warehouses, milk‑powder factories, and bulk stored grain; it also colonizes alfalfa leafcutter bee nests. A synanthropic, xerophilous pest.

Warehouse beetle (Trogoderma variabile Ballion) infestations are most clearly indicated by larval exuviae—the papery, tawny cast skins shed at each molt—mixed with kernels and fines. Other hallmarks include:

- Larvae, live or dead: setose, elongate, tapering posteriorly, often near the grain surface or in residues.

- Adults: small dermestids with mottled elytra, found on grain surfaces or near light sources.

- Visible kernel injury: pinholes and perforations, superficial grazing of the seed coat and embryo, partially hollowed kernels, and fine, powdery debris produced by feeding.

Warehouse beetle (Trogoderma variabile Ballion) has a holometabolous life cycle. Females oviposit randomly on dried plant or animal materials. Eggs hatch to mobile larvae that feed within the commodity, causing most damage. Larvae pass through multiple instars; under unfavorable conditions late instars enter facultative diapause, a dormant state that prolongs survival. When conditions improve, development resumes and pupation occurs in protected sites within the product or nearby crevices. Adults emerge, harden, mate, and disperse to colonize new lots. Under favorable conditions, egg‑to‑adult development averages 30–45 days, enabling rapid population buildup in storage.

This stored‑product pest is a generalist. Damage to stored grain arises exclusively from the larval stage: larvae invade kernels and consume internal tissues (endosperm and embryo), while sparing the outer seed coat (testa). The injury is not distinctive and may be overlooked during routine inspection. Infestations occur in bulk grain as well as in sacked lots and packaged, processed foods, since larvae can exploit seams and small openings. Adults do not damage grain; they are florivorous, feeding on nectar and pollen. In short, losses stem from internal kernel feeding by larvae across a wide range of commodities, including bagged grain and packaged foods.

Other species of the genus Trogoderma

Species of the genus Anthrenus

Species of the genus Anthrenocerus