Angoumois grain moth

Angoumois grain moth (Sitotroga cerealella) is a small moth. Adults measure 6–11 mm in body length, with a wingspan of 12–14 mm. The imago is pale grayish-brown to ochre-gray, slender, with narrow forewings. Labial palps are strongly upcurved. Freshly emerged adults show a distinct black spot (macula) on the apical third of the forewing. Larvae are white, up to 6 mm long, with poorly developed legs, and they do not leave the grain.

Larvae penetrate intact kernels through the pericarp and tunnel internally, consuming endosperm and often the germ. Feeding leaves kernels hollowed, mealy, and brittle, with conspicuous round perforations where the mature larva exits. Coarse frass and tunneling reduce test weight and milling quality, and seed lots suffer depressed viability and germination. Infested pockets become metabolic “hot spots”: grain temperature rises and intergranular moisture increases, promoting mold growth and caking, and creating a microhabitat favorable to secondary pests. Unlike many other lepidopteran pests of stored products, there is no webbing or clumping of grain. Adults do not injure the commodity.

Signs of infestation by the Angoumois grain moth, Sitotroga cerealella (Olivier), in stored grain: - Grain mass hotspots or self-heating, sometimes with localized caking and surface condensation, as larvae develop as internal feeders (endophagous) inside kernels. - Adults—small, straw‑colored moths with narrow, fringed wings—flying near bin openings, inspection hatches, or lights; sudden flight when grain is disturbed. - Kernels with pinhead‑sized, round emergence holes; many grains feel light or hollow when cracked. - Fine, floury frass and powdery screenings accumulating at the grain surface or beneath handling points. - Increased broken germ and mealy endosperm, with reduced test weight and poorer flowability in affected lots. Because feeding is concealed, external damage may be minimal until adult emergence. Routine temperature monitoring and visual scouting are key to early detection.

Angoumois grain moth (Sitotroga cerealella) reproduces entirely within kernels. Females oviposit up to ~150 eggs, singly or in small clusters, on grain surfaces or between kernels on maize ears—preferably at the tip where exposed grains occur. Embryonic development lasts about 7–10 days in autumn. Neonate larvae are mobile and quickly penetrate at the kernel–cob junction, then feed endophytically in the endosperm under a “hidden infestation.” Development rate is temperature‑dependent: roughly one generation per year in Central Europe, up to 12 in tropical climates. The final larval instar bores toward the pericarp, then pupates within the kernel. The imago completes eclosion and exits through a small emergence hole, leaving a hollowed grain and frass.

Preferred habitat: synanthropic stored‑product environments—granaries, warehouses, and silos holding bulk cereals. It prospers in warm, dry, poorly ventilated grain masses, infesting whole kernels; larvae are endophagous, developing concealed within the grain.

None.