Washington State Entomologists Ask: 'Have You Seen This Huge Moth?'

One of Earth's largest moths, with a wingspan of nearly 10 inches, has been spotted in the Pacific Northwest for the first time.

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Stock photo of Atlas moth held in two hands
I, for one, welcome our new moth overlords. (Entomologists disagree.)

Washington State entomologists are asking people to be on the lookout for a potentially problematic newcomer to the state: the Atlas moth. Fortunately, the insects are pretty hard to miss, with their nearly 10-inch wingspans and distinctive diamond markings.

“This is a ‘gee-whiz’ type of insect because it is so large,” Sven Spichiger, an entomologist at the state’s agricultural department, said in a WSDA press release (titled “Have you seen this huge moth?”). “Even if you aren’t on the lookout for insects, this is the type that people get their phones out and take a picture of – they are that striking.”

Spichiger and others are on alert after a single Atlas moth was spotted, identified, and captured in the city of Bellevue near Seattle last month. Experts are now trying to determine if the sighting was a one-off case of an escaped insect or if there’s a population of moths setting up shop in the area.

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Atlas moths are one of the largest moth species in the world. They’re second only in wingspan to the white witch moth (wingspan 14 inches) and arguably have the largest wing area of all known species. Their wing shape and markings are thought to be evolved to resemble the heads of snakes, as a means of warding off potential predators.

“It’s an incredibly beautiful moth,” Patrick Tobin, an entomologist at the University of Washington, told KUOW. “The snake head on the wingtips, it’s just an amazing design, and it’s such an incredible example of mimicry.”

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However, as beautiful as they are, Atlas moths aren’t a welcome sight for entomologists or farmers. The insects are native to Asia, from India to the Philippines and Indonesia. Their caterpillars are voracious eaters, and they can quickly defoliate trees and other plants. Atlas moth caterpillars are occasionally considered a crop pest, even in their home range, when they have a population boom.

And in the U.S., the species is considered a federally quarantined pest. It’s illegal to buy, keep, or sell live Atlas moths, caterpillars, eggs, or cocoons without specific USDA-granted permits.

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In Washington specifically, entomologists worry the state’s apple and cherry trees could end up as possible host plants for Atlas caterpillars. Washington is the U.S.’s largest producer of both apples and sweet cherries. Though, it’s unclear if the (mostly) tropical moths could even survive long-term in the northern state.

Other large, related moths are native to the United States, like Cecropia moths (the largest in North America) and Polyphemus moths. Please don’t squish them.

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The exact origins of the one moth found so far fluttering around Bellevue are unknown. However, KUOW reported that a local, now-defunct eBay account was selling Atlas moth cocoons for $60 each online. “This particular individual was bringing in cocoons from Thailand, which is highly illegal, and selling them on eBay, which is also highly illegal,” Tobin told the news outlet.

If you do happen to see anything you think could be an Atlas moth in Washington, officials want to know. Take a picture, note the location, and report it via email to pestprogram@agr.wa.gov. For sightings anywhere else in the country, photos and location info should be sent to local state plant regulatory officials or state plant health directors, according to the WSDA press release.