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Angoumois grain moths were first discovered chomping through grain stores in a former Provence of France known as Angoumois, but quickly spread across Europe and into the rest of the world with grain shipments. Because larvae feed inside of grains, it can be difficult to recognize an infestation in the field, causing entire grain stores to be tainted.
Angoumois grain moths are small, tan moths that reach about 1/2 inch long as adults, who are easy to distinguish from other moths by their fringed hindwings. These moths are serious pests of corn and other whole grains. Their lifecycle often begins in corn fields, where females carefully lay one egg per kernel on developing corn. When larvae hatch in about a week, they burrow into the corn kernel and begin to feed. After 25 to 64 days, the cream-colored, legless larvae mature after pupating inside the corn kernel and emerge to start the cycle all over again.
Infestations of Angoumois grain moths cause serious economic damage for farmers and small growers alike. Although fresh corn is a favorite, these moths also target stores of rice, barley, sorghum, millet, wheat and dried, shelled corn. When moths invade bins, damage is often less extensive than when they lay eggs in the field, however, since they can only access the top layer of grain.
Populations can get wildly out of control when larvae mature within grain storage facilities, where they have access to a variety of grains. Many generations are possible each year, with a new generation emerging about once a month in warm weather.
Control is sometimes difficult, especially in open corn cribs where fumigation is near-impossible. Some growers have seen great success with sex pheromone lure traps designed to attract males of the species, eliminating potential mates for females. Since the adult months don’t live more than a month, careful observation and timing can prevent further problems with these moths in small-scale storage facilities
Prevent future infestation by thoroughly cleaning bins before storing new grains, as well as carefully cleaning tools before harvest. Small stands of corn should be checked by hand and any infested ears discarded. Above all else, using your grains instead of storing them helps to break the life cycle of these pests.
Angoumois grain moths are no reason for concerns by themselves, but the feeding activity of the larvae give a variety of molds and bacteria an entry into stored grain. It is also possible that the presence of a population of Angoumois grain moths raise the temperature of stored grains, allowing pathogens to spread more rapidly.