It will be a well-above average year for miller moths across the northern Front Range, according to CSU entomologists Whitney Cranshaw and Frank Peairs.
The prediction is based on earlier reports that the caterpillar stage of this insect, known as the army cutworm, has been unusually abundant this spring and damaging to crops. The “miller moth” stage of the army cutworm occurs later as the caterpillars transform to moths and begin their annual migration from the plains to the mountains.
“The rainfall and good soil moisture of the northeastern part of the state will allow this year to be unusually good for blooming plants,” said Cranshaw. “If so, that will have an effect of spreading out the moths, rather than having them concentrated in irrigated yards. This may suppress, a bit, the incidence of them in/around homes.”
The moths already began to emerge in mid-May, earlier than normal, but are not expected to peak until the middle of June. Warm, clear, calm nights accelerate migration activity and moths are often most noticeable on days that follow a night favorable to flight.
Army cutworm caterpillars were not unusually abundant in southeast Colorado where there has been an extended drought, according to Cranshaw. This will result in normal or below average numbers of moths, but those that do appear will be concentrated around the sites of blooming plants.
Cranshaw and Peairs have produced an information sheet with questions and answers about miller moths that can be found at http://col.st/1n9VXzp.