Cadelle beetle

Adults of the cadelle beetle, Tenebroides mauritanicus (L.), have a glossy black to dark brown integument and measure 6–11 mm in body length. The larvae are whitish, contrasting with a strongly sclerotized black head capsule, a black pronotal (thoracic) shield, and paired black urogomphi at the abdominal apex. Larvae can reach 19 mm and move actively among stored commodities, aiding rapid dispersion within infested lots.

Primary injury occurs when larvae preferentially attack the germ (embryo) of kernels, clipping or hollowing the embryo and adjacent endosperm. This results in reduced germination, weight loss, diminished nutritional value, and downgraded milling quality. Both larvae and adults abrade kernels, producing fragmented grain, frass, and cast exuviae that contaminate lots. Feeding perforations and galleries predispose grain to secondary invaders (mites, storage fungi), fostering mold growth, off-odors, and quality defects. Field signs are often non-specific and not pathognomonic for this species. In storage facilities, late instars readily gnaw into wood and plaster to create pupation cells, generating powdery frass, weakening liners, partitions, and cribbing, and providing harborage in seams and crevices. Over time, such tunneling complicates sanitation and sustains reinfestation pressure.

Cadelle beetle (Tenebroides mauritanicus (L.)) infestations in stored grain are typically cryptic. The principal—and often the only—diagnostic sign is the presence of holes in surrounding structures, caused by larval boring. Such perforations and short larval galleries in adjacent materials attest to active development of the pest. Within the grain mass, other distinctive indicators are often absent; therefore, vigilant inspection for structural perforations around storage installations is key to detection.

The cadelle beetle (Tenebroides mauritanicus) completes its life cycle within stored grains and milled products. Females oviposit in batches of 10–60 eggs directly in the commodity and in crevices. After eclosion, elongate, campodeiform larvae feed voraciously and act as facultative predators, attacking other insects infesting stored goods. Larvae and adults can perforate flour sacks, cardboard packaging, and bolting cloth, facilitating spread within storage sites. Mature larvae form a cell in food residues, packaging, or wood and pupate; the teneral adult emerges, hardens, and mates. Adults are long‑lived and polyvoltine under favorable conditions, generating overlapping cohorts and sustaining continuous oviposition in storage facilities.

Prefers stored-grain habitats with old residues: mills, granaries, ships, silos, warehouses, and shops. Also infests farm-stored grain and dwellings; larvae bore in wood or plaster, creating galleries that serve as refugia for other stored-product pests.

Species of the genus Dermestes Species of the genus Alphitobius Mealworm beetle (Tenebrio molitor)