Miller moths are frequently encountered, especially during their migratory periods. The term “miller” refers to the dusty appearance caused by fine scales shedding from their wings, resembling flour dust on a miller’s clothing. Their feeding habits differ significantly between their adult and larval life stages. These diets directly support their life cycle and ecological functions within various ecosystems.
What Adult Miller Moths Consume
Adult miller moths primarily consume nectar from flowering plants. They use a long, flexible mouthpart called a proboscis to extract this sugary liquid. This nectar provides energy for their flight and reproductive activities. Some plants they frequently visit include lilac, cherries, spirea, cotoneaster, horsechestnut, raspberry, and Russian olive. Adult moths may also consume tree sap, supplementing their nectar diet.
These nocturnal insects embark on extensive migrations, often traveling hundreds of miles from plains to mountains in search of flower sources. They feed almost exclusively at night. While they may seek shelter in homes during the day, adult miller moths do not feed on household items or stored food.
The Diet of Miller Moth Larvae
The larval stage of the miller moth, commonly known as the army cutworm, has a significantly different diet from adults. These caterpillars are herbivorous, feeding on a wide array of plants. They consume agricultural crops, garden plants, broadleaf plants, and grasses like winter wheat, alfalfa, and turfgrass.
Army cutworms derive their name from their tendency to move across fields in large groups when food sources become depleted. They are voracious feeders, especially in their later developmental stages. Feeding primarily occurs at night, with caterpillars hiding in the soil or under plant debris during the day. Their habits can lead to considerable crop damage, as they may cut off seedlings or defoliate entire plants.
Ecological Role and Impact
Miller moths play a role in their ecosystems. As adults, they function as nocturnal pollinators, visiting flowers and inadvertently transferring pollen as they feed on nectar. This pollination contributes to the reproduction of flowering plants, complementing daytime pollinators like bees and butterflies. Their migratory patterns between plains and mountains allow them to access diverse floral resources and contribute to plant life across different elevations.
Adult moths and their larvae serve as food sources for other animals. Birds, bats, and spiders are common predators of adult miller moths. Grizzly bears, in particular, rely on the moths as a food source, sometimes consuming thousands per day by overturning rocks where they shelter. Army cutworm larvae are consumed by predatory ground beetles and various bird species.