Some people say "eww" and others feel awe about this nature news: Billions of flying insects called cicadas that have been underground since 2004 will emerge in huge swarms this month in some Eastern states. They don't bite or sting, but they're very noisy for two to four weeks. Ignoring their song (OK, racket) will be impossible for people nearby. Mating sounds can reach 100 decibels, as noisy as a gas lawn mower, revving motorcycle, farm tractor, garbage truck or outboard boat motor. Hard-hit areas could have more than a million cicadas per acre, scientists estimate. That's over 30 per square foot. Their "loud buzzing sound might make you think there's a generator running somewhere in the neighborhood," says The Washington Post.

These cicadas (pronounced suh-KAY-duhz) can be more than an inch long with a three-inch-wide wingspan -- larger than the usual green ones that show up annually in some regions. The upcoming visitors are classified as Brood X (Brood 10) and are known for bright red eyes, deafening choruses and a dramatic emergence every 17 years. Cicada eggs hatch into nymphs, which spend more than a decade below ground sucking juices out of tree roots. Then they pop out of tunnels they've been building for weeks in parts of 15 states from Pennsylvania down to northern Georgia and as far west as eastern Illinois. They'll creep out of dime-size holes in the ground and climb nearly any vertical surface, particularly trees, and transform into adults with wings.

Cicadas don't all appear at once, but it may sound like it by mid-May around Cincinnati, Philadelphia, Baltimore, Indianapolis and Washington, D.C., experts predict. They die naturally in four to six weeks after mating and laying eggs that stay buried until the next cycle in 2038. "By having the long life cycles, cicadas have prevented predators from specifically targeting them for food," says Gary Parsons, an insect scholar at Michigan State University. "Then by emerging in the millions all at once, they are too numerous for any predators that do eat them from ever wiping them out. There are so many of them that lots of them will always survive." Don't be grossed out, advises another expert, Mike Kasson of West Virginia University, who suggests we should "just marvel in the fact that you're witnessing something that no one else in any other part of the world gets to see. And it's right in your backyard."

Yard plants are safe: Cicadas don’t eat plants, so flower and vegetable gardens won't be harmed.

Don't let pets gorge: Eating a few of the bugs won't sicken dogs and cats, but overdoing it might.

They're not locusts: Cicadas may seem like a plague, but are unrelated to crop-eating locusts that appear in the Bible and Torah. Locusts are a type of grasshopper, a different species.