Longheaded flour beetle (Latheticus oryzae)

Latheticus oryzae (Waterhouse), the longheaded flour beetle, is a small tenebrionid (~3 mm) with a slender, dorsoventrally flattened body. Adults are yellowish to brownish, with a relatively large, elongate head and short, clavate antennae bearing a five-segmented club. The habitus is narrow and depressed. Larvae are pale yellow to cream, weakly sclerotized, with a contrasting dark head capsule and dark, paired urogomphi at the apex of the abdomen.

Damage in stored grain is non‑distinctive: both adults and larvae feed directly on the commodity. A secondary pest, it exploits cracked kernels, broken grain, and fines. Using rasping‑chewing mouthparts, it abrades the pericarp and endosperm, hollowing fragments and converting material to dusty meal. Feeding generates powdery frass mixed with cast larval skins and insect fragments, contaminating lots and increasing dockage. Aggregations create warm, slightly moist pockets that favor mold development and musty odors, while flouring of material can cause caking and surface crusts in bins. Continued activity lowers mass and test weight; in seed lots, incidental injury to the germ can reduce viability. In short, the product is eaten and powdered, then adulterated by frass and insect remains, without distinctive lesions that separate this damage from that of other secondary stored‑product beetles.

Key signs of infestation by the Longheaded flour beetle (Latheticus oryzae Waterhouse) in stored grain: - A musty, unpleasant odor emanating from the commodity, often linked to secondary fungal growth. - Abundant beetles: slender, pale brown adults with an elongate head and prothorax; creamy, cylindrical larvae bearing paired terminal urogomphi. - Aggregations in warm, damp pockets—near surface layers, bin corners, bag seams, or under caked grain. - Excess fines, frass, and cast larval exuviae, giving a mealy, dusty appearance. - Feeding concentrated on broken kernels and milled fractions; mold-softened grains may appear eroded or partially hollowed. - Development of hot spots, caking, and localized moisture, frequently accompanied by mold bloom and discoloration. - Overall downgrading of commodity quality: off-odors and taint, indicating deterioration rather than primary kernel boring.

Latheticus oryzae (longheaded flour beetle) is holometabolous. Females carry out scattered oviposition, depositing eggs at random within stored commodities. A high thermal minimum—about 25°C—is required to complete development; below this threshold the life cycle arrests. Larvae, from neonates to later instars, are highly mobile within the grain or flour mass, actively dispersing through the lot. After larval development, pupation occurs and adults emerge, mate, and renew infestation.

Latheticus oryzae is thermophilic and hygrophilous, thriving in warm, humid grain masses in mills, granaries, and ship holds; cold suppresses its development.

Ténébrion olifant (Gnatocerus cornutus): broadhorned flour beetle (Gnatocerus cornutus). Ténébrion de Ratzeburg (Palorus ratzeburgii): small-eyed flour beetle (Palorus ratzeburgii). Espèces du genre Tribolium: species of the genus Tribolium.