Indian meal moth (Plodia Interpunctella)

Type of pest: Secondary pest.

Distribution: Worldwide, especially warm temperate to tropical regions.

Identification: Adult labial palps point forwards. The forewing (7 – 9 mm) is bi-colored cream and reddish-brown. Larvae are 15 mm, in unmarked creamy white, with the rim of abdominal spiracles evenly thickened.

Similar species: Cadra, Ephestia, Corcyra, however fresh specimens are distinctive.

Life cycle: Optimal conditions in 30 days at 30 ºC, 75 % r.h. Eggs are stuck to the commodity. Larvae are external feeders, and produce silk webbing. Adults are short-lived, do not feed on the commodity and can fly.

Commodities infested: Dried material of plant origin, especially cereal products, oilseeds, cocoa, chocolate, spices, nuts, dried fruit and processed foods. Direct damage to grain is the result of larvae feeding on the seed germ. Only broken kernels of grain and grain dust are attacked as larvae cannot penetrate undamaged grain. Larvae cannot chew through packages, so they must enter through a hole or at the seam.

In grain to be sold for human or animal consumption, the Indian meal moth feeding reduces the dry weight. At the same time, grain weight may actually increase because of water absorption; with an increase in water content mold can become a problem. The biggest reduction in value is the result of contamination by larvae that leave droppings and silken webs in the grain. The presence of live insects and insect parts can result in dockage of the grain when sold. The webbing also sometimes clogs milling machinery.

Treatment: Controlled Atmosphere for infestation in product
Treatment: Heat Treatment for infestation in buildings