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Montana's fearsome looking cicadas often misunderstood

Montana's fearsome looking cicadas often misunderstood

Tibicen dealbatus
The largest of the Montana cicadas, Tibicen dealbatus (Davis), hatches on the plains of Eastern Montana in mid-summer each year.

At the bug lab in Bozeman, they call the 2-inch long critter the "the big green one," the largest of Montana's cicada species.

Tibicen dealbatus (Davis), a bug that looks like it flew off a horror movie set and into Billings' backyards, is an annual summer visitor to plains of Eastern Montana.

Although its bulging eyes give it a prehistoric appearance, its transparent veined wings are more reminiscent of Peter Pan's Tinkerbell.

Cicadas are often confused with the Biblical locusts, but locusts belong to the grasshopper family. And Montana's cicadas are not the infamous periodical cicadas, always catching headlines when they hatch, en masse, once every 13 or 17 years.

Tibicen dealbatus, which hatches annually in mid- to late summer, is more often heard than seen.

"They're the guys that make the big chainsaw noise up in the trees," said Amy Grandpre, with the Yellowstone County Extension Service.

The male sings, but he's no Sinatra.

Their cacophonous screeching sound can be heard for a very long distance, said Michael Ivie, the curator of the Montana Entomology Collection at Montana State University in Bozeman. Fortunately, the males confine their singing to daylight hours.

"When they get together, it's quite an earful," Grandpre said. "On canoe trips, on some patches of the river, it will just be deafening."

Unlike crickets, which make sounds by rubbing wings or legs, cicadas have timbals, membranes and rib-like structures on their abdomens, which move to make a drumming sound that resonates through their bodies.

"At higher temperatures, they'll actually sing a shorter amount of time because they'll get through the song faster," Ivie said.

Both males and females will make angry, clicking sounds if they're picked up or otherwise disturbed.

One Blue Creek-area homeowner was startled by a cicada that flew into his garage. For an instant, he mistook it for a hummingbird, until it crashed into a window and he saw it crawling around.

Adult females insert hundreds of eggs into slits they make in the bark of tiny branches. When the nymphs hatch, they drop to the ground, and then use their strong front legs to burrow into the ground, where they suck sap from tree roots.

In Montana, the immature nymphs live underground for about five years before they crawl to the surface, climb a tree, shed their shell-like skin and molt into adults.

"A lot of people will see the brown shell that's leftover when they emerge, and that kind of creeps them out," Grandpre said.

Most species of cicadas don't eat during their brief adult lives. Despite their frightening appearance, they don't bite or sting.

"They're basically just a mating and egg-laying device," Ivie said. "They're there to have sex, lay eggs and die."

A large cicada hatch spells a feast for birds, and probably also for shrews, foxes and coyotes.

"They're quite nutritious," Ivie said.

In some cultures, people eat cicadas

"They are large, fat-filled animals that can be fried," Ivie said.

A search of the Web turns up many recipes including tacos and a rhubarb pie on the National Public Radio site, along with the warning that cicadas have been known to trigger allergic reactions.

Contact Donna Healy at or at 657-1292.



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