How did miller moths get their name?
There is more than one explanation and here are two. One, the wings of all moths are covered with fine scales that easily rub off. These scales reminded people of the dusty flour that covered the clothing of the miller. Also, the insects are known for “milling” around light sources.
Look out Mothra.
It’s not a scene from a cheesy Japanese science fiction flick, but swarms of pesky, messy miller moths have descended on the Golden Belt on their annual migration westward.
Although harmless, “they can be a pretty big nuisance,” said Phil Sloderbeck, a Kansas State University Extension entomologist out of Garden City.
“Miller” is a loosely used term generically applied to a number of different moth species. However, the variety invading the area now are the matured army cutworms.
These moths are generally gray or light brown and have wavy dark and light markings on the wings. The wing patterns of the moths are quite variable in color and markings.
“This is an interesting insect,” Sloderbeck said. The eggs hatch in the fall and they begin their lives as larva that feed on early spring crops across the Plains states.
At this stage, they do the most damage, gnawing on fledgling alfalfa, wheat and other plants. The tiny, fuzzy green worms pupate in mid spring and emerge as the more visible moths.
“Then they migrate west to the Rocky Mountains,” Sloderbeck said. This migration can be as long as five to six weeks though most of it is concentrated in a two to three period.
While in the high, cool Colorado air, they feed on nectar of summer wild flowers. As summer wanes, “they fly back in the fall and start another cycle,” the entomologist said. The fall migration is less noticeable since there are fewer moths making the trip.
Each female moth is capable of producing between 1,000 and 3,000 eggs.
The number of millers pestering area residents varies from year to year, and the number depends on a couple of factors, Sloderbeck said. “It’s more weather related.”
First, it depends wind directions and speed. Tossed by the gusts, they can wind up anywhere from Texas to the Dakotas while making their trek to the mountains. This means some areas may not get any, some might get a few and some might be inundated.
Second is survivability. In some years, fewer larva make it through winter or fewer moths make it through the summer. Food ability and weather conditions impact this, Sloderbeck said.
The moths fly at night and seek shelter during the day, he said. Ideally, this shelter is dark and tight. Small cracks in doorways of homes, garages and cars make perfect hiding spots. Often, many moths may be found sheltered together.
According to K-State Research and Extension, moths that have recently emerged from the pupa produce a reddish-brown fluid. This is the waste product stored during pupal development and is usually easy to remove.
If moths can’t find there way out of the home, they will eventually die and may serve as food for carpet beetles and other household scavengers. If large numbers die, there may even be a small odor problem.
The main complaint, though, is about the moths milling around lights both inside and outside. Most scientists believe moths are attracted to the light because they use the moon to help orient their flights and artificial lights confuse the insects.
However, if one does want to batten down the hatches, they can, Sloderbeck said. They can tighten cracks, use fewer lights and open and close the door less. Yellow, non-attracting light bulbs can also help.
Insecticides have little or no effect in controlling millers. The moths are not very susceptible to insecticides. Furthermore, any moths killed will rapidly be replaced by new moths that migrate into the area nightly.
“Getting them with a fly swatter and vacuuming them works better,” he said.
A vacuum can also be an easy way to catch the moths when they are at rest. A light bulb suspended over a partially filled bucket of water plus detergent can be used to trap them. Moths attracted to the light often will fall into the water and can’t escape.
On the plus side, the millers help pollinate plants.