Indian Meal Moth & Confused Flour Beetles
The Indian meal moth, is a very common food-infesting pest. It is a general feeder on grain and grain products, dried fruits, seeds, nuts, powdered milk, chocolate, candies, and some spices. Occasionally pet food and birdseed for outdoor feeders become infested and cause problems when stored indoors.
The adult moths are 7-9mm long and have a wingspread of 20mm. The forewings are pale grey with the outer portion of the wing a reddish-brown to copper color. The adults are often seen flying around lights in the house in the evenings. The female moths lay up to 300 eggs just below the surface of stored grains and other food materials. Eggs may be deposited through cotton or jute bags containing food.
The larvae are dirty white in color, but may be yellow, pink, brown or green, depending on the source of food. The larvae are superficial feeders and leave silk trails wherever they crawl. When an infestation is heavy, food materials may be completely matted with webbing. Often prior to pupating, the larvae wander from the food source. They may be observed crawling on ceilings or around the cupboard, away from the original food source.
Complete life cycles may take from 27 to 305 days, depending on environmental conditions such as temperature. There are generally 4 to 6 generations per year, but under favorable conditions there may be 7 or 8.
The confused flour beetle, and the red flour beetle, are common pests of stored grain and grain products. The adults of these two species are similar in life history, habits and appearance. Differences between the two species include slight variations in the antennae and the shape of the thorax. The antennae of the red flour beetle is abruptly club-like, the club consisting of four segments. The thorax of the red flour beetle is curved, whereas that of the confused flour beetle somewhat straighter.
The adults of the red flour beetle can fly short distances. Adults of the confused flour beetle do not fly. These beetles infest cereal products but feed only on damaged grain. Other materials attacked are peas, beans , shelled nuts, dried fruits, spices, milk chocolate, and herbarium and insect specimens.
Flour beetles feeding on grain products impart a disagreeable taste and odor to the product, by a secretion from their scent glands. Adult female flour beetles lay 2 or 3 eggs each day, up to 300-400 eggs in total. The average oviposition period for the red flour beetle is 5 1/2 months, and for the confused flour beetle, 8 months. Eggs are colorless to white, and are covered with a sticky material, often causing food particles to adhere to the outside. Hatching occurs after 9 days at room temperature. Larval development occurs over a period of time depending on food sources and temperature. A complete generation can develop within 2-4 months.