As Millions of Moths Migrate to Colorado, Insect Scientists Advise Turning Off Porch Lights

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Millions of moths have begun migrating to cities in the Colorado Front Range, a weather-driven seasonal surge that scientists predict will reach unprecedented intensity this year, from now until around early July, when moths will fly to the mountains.

They play a key ecological role as food for birds, bats, spiders and bears. They are nocturnal feeders, motivated to suck nectar through their long, straw-like proboscis mouths – favoring suburban homes with irrigated lawns and gardens decorated with white and cream flowers.

And rather than eliminate moths or eliminate them as pests, experts say human residents of Colorado should take a smarter approach — one that would also benefit fireflies, migratory birds and other creatures. nocturnal vessels that depend on moonlight and starlight for navigation.

“Turn off the lights on your porch,” said Shiran Hershcovich, head of lepidopterists at the Butterfly Pavilion in Westminster, where projects include firefly and moth conservation programs.

“When people think of pollution, they often think of ‘classic’ pollution, like a chemical factory dumping toxins into a river. But pollution comes in many forms, including artificial light that disturbs nocturnal animals,” Hershcovich said.

“If there is a light and a hole, the moths will find a way in.” When it comes to a bedroom window leading to a reading lamp, moths repeatedly pound the bulb. “They use it as a source of navigation. They think it’s the moon or some other celestial object,” she said.

Human complaints about moths have become almost as predictable as the annual migration.

Wailing makes no sense, said Maia Holmes, a Colorado State University entomologist who runs the Bug Zoo on CSU’s main campus in Fort Collins — a collection of hundreds of insects and insects. spiders open for public viewing.

“The whole concept of ‘pest’ is boring. We’re saying they don’t deserve to be here because humans find them boring? It’s selfish of humans to say another species shouldn’t be here because we find it irritating,” Holmes said.

When moths bump into lights, “have some compassion” and turn off the lights, she said. “They’re lost and confused, just trying to get somewhere.”

The migration begins on the high plains of Colorado where the adult butterflies lay their eggs about a centimeter underground – many of them this year due to the relatively mild winter. These hatch in early spring, traditionally in March, giving rise to an army of cutworm caterpillars (Euxoa auxiliaris) the size of a grain of sand. The worms eat through vegetation, cutting through the stalks of wheat and corn, quickly reaching the size of a child’s index finger. They then transform into winged moths, commonly called “suckers” because of their fine scales that stick out, resembling the dusty flour on the clothes of suckers.

A healthy butterfly can fly more than 100 miles from plains to mountains as high as the treeline.

Most will not return. But some adults return to the plains around September.

Moths are harmless, scientists have said. They do not carry diseases. They cannot sting or bite. Often, when they are numerous, the birds follow them in search of food.

So why not crush them anyway?

Moths have evolved a defense mechanism called “rectal charging” which is triggered by artificial light. “If they’re fussing around your house, they can ooze a dark fluid onto your walls and clothes,” Holmes said.

This bitter brown liquid is not harmful, she says. “It just tastes bad – to discourage you from eating it.”

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