A “miller moth” is an all-inclusive umbrella term used to describe any plain brown drab moth. In some areas of Kansas, moths have been a big nuisance to homeowners recently. At this time of year, the ‘miller moths’ are actually army cutworm moths, Euxoa auxillaris. They live on flower nectar and are not know to cause a lot of damage, but are quite an annoyance.
The seasonal life history of these moths begins in the fall of the year when adult moths deposit eggs in the soil in fields of fall-seeded wheat, alfalfa stands and weedy fields/patches. Eggs may hatch within several days of being deposited but may be delayed under unfavorable/dry conditions. Larvae preferably feed during the dark of night and seek shelter in the soil during daytime hours. Army cutworms overwinter as partially grown larvae.
Each year in the Kansas, overwintered army cutworm larvae resume their feeding as temperatures moderate and become warmer. They complete their development toward the beginning of May after which they burrow into the ground where they create protective earthen cocoons inside of which they pupate.
The nuisance is temporary
Moth emergence usually begins by late May. In some years the numbers of moths can be quite a nuisance. For a period of time, moths remain near areas where they emerged, this is the time period we are in right now.
The nuisance is temporary because at a certain point, an undefined stimulus (likely photoperiod driven) signals moths across the Central Plains states to migrate westward to the higher elevations in the Rockies where they are a food source for grizzly bears.
This is an interesting tidbit about army cutworm moths. During summer months, bears move to the higher elevations to feast on army cutworm moths. It was determined that a single moth possesses ½ calorie of fat content. It was further estimated that a bear obtains 20,000 calories of fat on a daily basis by consuming up to 40,000 moths per day.
In mid- to late September, the mature moths migrate back to the Central Plains where they deposit eggs to initiate the next generation of army cutworms.
These moths shun daylight and are much more active during the evening hours. That is, with the approach of daylight, army cutworm moths seek shelter/cover in any conceivable space including homes, garages, cars, and more. Excluding moths is difficult because they will exploit very small openings.
Prevention is the primary way to deal with the temporary army cutworm moth outbreak while we wait for their migration west. Seal around doors and windows to keep them from getting inside. It is recommended to reduce or turn off any unnecessary lights inside and outside the house to prevent the worms and moths from being attracted to your property.
Once in the home, the best way to remove the moths is to swat or vacuum them, or attract them to traps. An easy trap to make is to suspend a light bulb or lamp near or over a bucket partially filled with soapy water. Moths attracted to the light often will fall into the water and be killed.
Insecticides have little or no place in controlling millers. The moths are not very susceptible to insecticides and any moths killed will be rapidly replaced by new moths until they migrate west.