By Karen Morfitt

THORNTON, Colo. (CBS4) – Images showing swarms of miller moths have started to take over social media and researchers at Colorado State University says this year you’ll be seeing more of them. Dr. Frank Peairs is a professor of entomology, who along with another researcher track the movement.

(credit: CBS)

“It’s just one of those bug things,” he said about the arrival here in Colorado.

But for those trying to keep them out of their homes, like Gina Dooley in Aurora, the feeling is quite the opposite, “I absolutely hate them.”

Love them or hate them– they’re back, and earlier than in previous years.

For those dealing with hundreds of moths swarming around the lights around their homes it may feel like a record year, but Peairs says this is considered average.

“It’s been below average for the last four years, so people have kind of forgot about them,” he said. “An average year means some people will be bothered by them and some won’t. In a bad year, everybody is bothered.”

(credit: CSU)

Peairs says the moths originate in fields across eastern Colorado, Kansas and Nebraska and migrate west to spend the summer feeding on flowering plants in the mountains and can be quite harmful to crops.

He says if Front Range residents are seeing more of the pesky bugs it’s because of drier conditions this year compared to last, reducing the number of blooming flowers.

According to their research, a freeze in mid-April only added to the lack of blossoms from plants, leading to higher concentrations of moths in irrigated landscapes like yards and gardens.

He says along with the flowers, there’s another attraction.

“The other part of it is they are attracted to lights, so urbanized and suburbanized areas are going to be attractive areas for them,” said Peairs.

While they are harmless to most, those that do make their way indoors can be a nuisance, and for some even a bit frightening. But most say dealing with the miller moth is a sacrifice that comes with living in Colorado.

(credit: CBS)

“I am definitely used to it, but I think I forget,” Dooley said.

The good news is Peairs says they will not stick around forever and warm nights will speed up their migration. He says they are typically back east by fall.

Miller Moth fast facts from CSU:

Why are they called “miller moths?”

Fine scales that easily rub off cover their wings. The scales reminded people of the dusty flour on the clothing of grain millers.

What was the heaviest moth flight in recent history?

Since at least the early 1980s, the heaviest, most prolonged flight of miller moths across eastern Colorado occurred in 1991.

What eats them?

They have many natural enemies, including predatory ground beetles, hunting wasps, and many birds. Grizzly bears in Yellowstone are known to feed on large numbers of the fat-rich moths they find under loose rocks.

What are those swallows doing circling my car?

A commonly observed phenomenon during miller time is swallows – which love to eat miller moths – congregating at road intersections. This can occur because moths that had sought shelter in car chassis are warmed by the engine and emerge while the cars are idling at a stop light.

How do the moths get inside a house?

They avoid daylight and seek shelter before daybreak. Small cracks in doorways, garages and cars are perfect hiding spots. At night, they emerge to resume their migratory flights and to feed.

Why are moths attracted to lights at night?

Moths, and many other flying insects, are confused by low-point light sources because they naturally use the moon or stars to orient their flights.

Are miller moths harmful?

The caterpillar stage can be a pest for crops in the spring, and they can kill seedling plants. Mostly, the adults are just a nuisance. Moths in the home do not lay eggs or feed on household furnishings or food. If large numbers die in a home, there may be a small odor problem due to the fat in their bodies turning rancid. Large numbers can leave spots on walls from their meconia, which is waste stored during pupal development.

How do I control miller moths in my home?

Seal obvious openings around windows and doors. Reduce lighting at night in and around homes. An easy trap to make is to suspend a light bulb over a bucket partially filled with soapy water (always use a grounded plug and extreme caution with any electrical device near water). Moths attracted to the light often fall into the water and are killed. Moths are not very susceptible to insecticides.

What is extreme fear of moths called?

Mottephobia.

Much more information can be found at the CSU Extension fact sheet on miller moths.

Karen Morfitt

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