Khapra beetle

Larva: densely setose, reddish-brown at maturity, 4.5–6 mm long. Equipped with specialized setae—hastisetae and spicisetae—with conspicuous tufted fascicles on the terminal abdominal segments. Adult: a small, oblong dermestid (1.4–3.4 mm), uniformly reddish-brown. Females are slightly larger and paler than males. Elytra unpatterned, lacking distinct maculation. The overall aspect is compact and low-profile, with clean, featureless elytral surfaces that emphasize the species’ uniform coloration.

Early instars scavenge on pre-damaged grain fragments and fines, grazing exposed endosperm. As they progress to later instars, they attack intact kernels, perforating the pericarp and hollowing the endosperm and germ. Under heavy infestation, feeding reduces lots to powdery frass with abundant exuviae and larval setae, effectively destroying the commodity. Consequences include marked weight loss, reduced test weight, elevated dockage, off-odors, and loss of seed viability. Feeding foci generate hot spots that raise moisture and promote secondary mold development and mite proliferation, accelerating spoilage throughout the bin. Contamination by frass, cast skins, and hairs renders grain unfit for human consumption and severely downgrades feed value.

Early evidence is the build-up of larval exuviae (cast skins)—light, papery flakes—accumulating on the grain surface, in seams, and crevices. Look for live, setose larvae of Trogoderma granarium Everts, rust-brown with a distinctive posterior hair tuft (caudal brush), and small, dark, sluggish adults. Feeding injury includes perforated or hollowed kernels, gnawed embryos, and a rise in fines and frass. Infested pockets often develop hot spots from insect respiration, with localized moisture, caking, and musty/rancid odors. Surface activity when disturbed and aggregation along warm margins further support a Khapra beetle diagnosis.

Khapra beetle (Trogoderma granarium) reproduces within stored commodities. Females oviposit among grain. After hatching, larvae pass through multiple instars with repeated ecdysis; the life cycle is highly plastic. When conditions are favorable, larval development is faster and involves fewer molts. Under adverse conditions, larvae enter facultative diapause—sometimes lasting up to 8 years—triggered by cool temperatures, poor food quality, and population-density stress. Adults do not fly and do not feed. This species dominates in very dry grain, outcompeting other storage insects that tolerate low humidity less well.

Xerophilous and thermophilic, the Khapra beetle (Trogoderma granarium) thrives in hot, dry grain stores—granaries and warehouses—especially in tropical and subtropical regions, favoring 30–40°C and low RH with minimal grain moisture.

Other species of the genus Trogodermato.