Drugstore Beetle

The drugstore beetle, Stegobium paniceum (Linnaeus), is a member of the family Ptinidae (formerly Anobiidae), order Coleoptera. Adults are typically 2.25-3.5 mm long, unicolorous reddish-brown, possessing a distinctly humped prothorax, deeply punctate striae on the elytra, and conspicuous clubbed antennae. The life cycle, from egg to adult, averages 40-50 days under optimal conditions (30-32°C, 60-90% RH), but can extend to 7 months or more in cooler environments. Females lay 20-100 eggs singly in suitable food sources, with larval development progressing through 3-5 instars before pupation within a silken cocoon incorporating food particles. Larvae are C-shaped, cream-colored, and densely covered with fine hairs, reaching up to 4 mm in length.

Stegobium paniceum adults are primarily crepuscular and nocturnal, showing positive phototaxis, often congregating around windows or light sources. Dispersal occurs through both flight and passive transport, with strong flight capabilities enabling infestation spread throughout structures or into new facilities over considerable distances. Communication relies on pheromone signaling, with females producing a sex pheromone to attract males. Larvae are internal feeders, creating galleries and tunnels within their food substrate. Unlike many stored product pests, S. paniceum possesses symbiotic yeasts that produce B vitamins, allowing it to thrive on nutritionally deficient materials; this broad dietary niche contributes to its pest status across an exceptionally wide range of commodities, from pharmaceuticals to dried plant materials.