Environmental conditions lead to more moths


The year 2020 has

brought a deep economic decline, the

coronavirus – might as well bring on

pestilence.

Miller moths – the adult stage of the

army cutworm – are being reported in

numbers not seen in Nebraska and Colorado

for at least five years, and up to

19 in some locations, according to Scott

Schell, University of Wyoming Extension

entomologist.

Wyoming towns are also being visited

as the moths follow the timing of

the flowering plants into the high country.

“I have talked to people around the

state, and the millers are very widespread

this year,” Schell said.

He said conditions for survival and

reproduction have been good the last

year or two.

Moth abundance in towns can be due

to dry conditions in the country with

few flowering plants to feed on at night,

he said. The moths are then drawn into

watered landscapes and towns to find

flowers.

“I think there is a combination of

that going on this year,” said Schell.

“The eastern plains had more reports

of crop damage to alfalfa and winter

wheat caused by the miller moth larvae,

called cutworms, than usual. That was

followed up by dry conditions on the

sagebrush steppe and prairie producing

few wildflowers for the moths to gather

nectar at.”

The starting point of miller migration

probably comes down to wind and

weather, he said. A cold front from the

north probably grounds the moths until

it passes, and warm breezes from the

south are the ticket to travel long distances

at night.

Schell recommends turning off outdoor

lights or switching to yellow insect

lights to minimize their annoyance.

“Checking your window screens and

weather seals for cracks big enough to

let them in and fixing them helps exclude

them when they seek out places

to hide for the day,” said Schell.

He advised checking screen doors.

“I also have a light I can turn on

away from my entry door to the house

on my attached garage, which acts as a

giant miller moth trap at night,” he said.

“The light draws the millers away from

the door.”

Schell said miller moth numbers in

towns should taper off soon as the survivors

migrate to the high country.

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