GRAIN PESTS

Common names: Grain Beetle, Grain Moth, Grain Weevil

Scientific name: Many orders, families, and species

Size: Varies greatly

Identification: Varies greatly

Biology and life cycle: Insects whose larvae and adults eat grain. They are particularly a problem in large grain-storage vessels and buildings.

Habitat: Stored raw grain such as rice, milo, corn, soybeans, peanuts; also stored processed products such as cereal grains, cake mixes, flour, and cornmeal.

Economic importance: Destruction of large volumes of grain.

Natural control: Beneficial predators and parasites can be purchased to control grain pests.

Organic control: Pheromone traps, spraying the walls of storage vessels and the top of grain with Bacillus thuringiensis. Treating grain with natural diatomaceous earth. Releasing trichogramma wasps and other beneficials. Use Bt for moths and DE for beetles and weevils.

Insight: Grain beetles, moths, and weevils are all troublesome insects. One problem with the use of DE in stored grain is that it is abrasive to the grain-handling equipment.

Xylocoris flavipes, the warehouse pirate bug, is used for control of larvae, eggs, pupae, and adults of all species of beetles and moths (except the larvae and pupae of the Angoumois grain moth, which develop inside the seed).

Trichogramma pretiosum, a moth egg parasite, deposits eggs within the eggs of moths. The complete life cycle of these parasites occurs within the host eggs. On the ninth day following parasitism, the adult parasites emerge from the host egg.

Bracon hebetor, a moth larval parasite, deposits eggs on the exterior of all moth larvae (except those of the Angoumois grain moth). Hatching larvae consume the fluids of the pest larva and form cocoons adjacent to the carcass of the expired host or pest insect. Adult parasites hatch from the cocoons in twelve to fourteen days to repeat the beneficial cycle.

Anisopteramalus calandrae, a parasitic insect referred to as AC, stings the weevil larvae within the infested seed and deposits her eggs there. Hatching larvae consume the body fluids of the pest (host) larvae, form a cocoon, and emerge from within the seed in twelve to fourteen days as adult parasites to repeat the cycle.






 

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