U.S. Midwest expects this month the emergence of billions noisy cicadas, that spent 17 years underground.
"It's one of the greatest insect emergences on Earth," said Daniel Summers, an entomologist at The Field Museum in Chicago.
The red-eyed, shrimp-sized, flying insects do not bite or sting. But they are known for mating calls that produce a sound that can overpower telephones, lawn mowers and power tools. Almost all burst from the ground within a couple days of each other, then quickly climb the nearest vertical surface to molt and unroll their wings.
In some heavily wooded areas, as many as 1.5 million cicadas per acre (0.4 hectare) will crowd onto trees, experts say.
This year's emergence, called Brood XIII, is expected in parts of Illinois, Iowa, Wisconsin, Michigan and Indiana. Cicadas live only about 30 days as adults, and their main goal is mating.
They do not harm humans, although they are clumsy and might fly into people. Birds, squirrels and pets, especially dogs, love to eat them, and they are high in protein.
Periodical cicadas are found only in the eastern half of North America. The annual cicadas that appear every summer are common around the world.
The last massive emergence of periodical cicadas was in 2004, when Brood X emerged after 17 years underground in parts of 15 Eastern states. Some broods emerge after 13 years.
A single male's shrill courtship call can reach 90 decibels, equivalent to a kitchen blender. That could spoil plans for outdoor events over the next few weeks.
Ravinia Festival, a 103-year-old music festival held north of Chicago, revised its schedule to avoid classical musicians having to compete with the insects, said festival president and CEO Welz Kauffman.
An Illinois company that provides ice sculptures has turned down several outdoor parties over the next month. That is because of what happened when Nadeau Ice Sculptures owner Jim Nadeau delivered a swan statue to a wedding in 1990, during the area's last emergence.
"We put our tray down and immediately the cicadas came off the ground and attacked the ice. Literally, it was a moving sculpture, this big black ugly mass of cicadas constantly moving," said Nadeau.
"I don't want to talk myself out of work, but that was just too gross," he said.
Exactly when the cicadas will emerge is a subject of debate. Biologists and insect experts predict the cicadas will emerge between Tuesday and June 1.
David Hammond runs an Chicago-based Internet site devoted to culinary matters, and his friends want to see what the cicadas taste like.
The insects are eaten in other parts of the world, with descriptions of the taste ranging from shrimp to canned asparagus.
Hammond assumes the cicadas will be fried and perhaps accompanied by a dip or salsa.
"Honestly, they'll probably go down easier that way," he said. "Who knows? Maybe we'll love it. We may have to travel around the country as infestations occur."