Meal moths (Pyralis farinalis) belong to the Pyralidae family and considered as cosmopolitan pests because of their abundance in rural and urban settings where stored food items are present. These insects belong to the same order (Lepidoptera) as butterflies albeit with less colorful appearances.
The larvae have a whitish appearance with body length ranging from 20 to 25 millimeters without black spots while the heads are distinctly brown. Their first body segments usually have black thoracic shields.
The adults are usually patterned in colors ranging from light to dark brown while many specimens can have bluish or yellowish variations. These moths are relatively colorful in comparison with other moths especially on their upper wings. Their wingspans range from 18 to 30 millimeters.
Females can lay between 250-500 eggs. For as long as there is a food source for the larvae, the eggs will be laid loosely and randomly.
At rest, adult meal moths hold the tips of their abdomens at right angles – 90 degrees – to their bodies. Such stance provides an interesting study in posture for these insects. Their flying activities happen mostly at dusk and dawn while the day is spent resting on walls and other surfaces. The adults fly in from June to August in most regions.
Meal moths are found in virtually every corner of the globe but their most common habitats are in temperate regions like North America. As proof of their hardiness in cold temperatures, these insects can overwinter in unheated granaries from the United States to Canada especially in these countries’ prairie regions.
These pests can be found in mills, grain elevators, warehouses, grain ships, and household, all of which have an abundant food supply consisting of coarsely-ground cereal products, high-moisture content cereals, decaying cereals, and moldy grains, among others. Larvae prefer wheat, oats, corn, barley, peas, peanuts, beans, dried fruit, potatoes, flour and mixed feed as well as processed cereal.
The meal moths’ larvae are active creatures. These can burrow into food including its packaging and then create silk tunnels where concealment while feeding is possible. Sings of infestation include contamination of the packaging with pupal cases, frass, cast skins and even adult remains. Such diet makes meal moths a costly problem for many businesses including cereals and grains processing plants while homeowners will experience food wastes from cereals and other dried food items thrown away after signs of infestation are confirmed.