Any day now, billions of cicadas with bulging red eyes will crawl out of the earth after 17 years underground and overrun the east coast of the US, scientists say.
They will arrive in such numbers that people from the southern state of North Carolina to Connecticut in the north east will be outnumbered by roughly 600-to-1.
But ominous as that sounds - along with scientists' horror film name for the infestation, Brood II - they are harmless. The insects will not hurt humans or other animals - at worst they might damage a few saplings or young shrubs. Mostly they will blanket certain pockets of the region, though lots of people will not ever see them.
"It's not like these hordes of cicadas suck blood or zombify people," said May Berenbaum, a University of Illinois entomologist.
They are looking for just one thing - sex. And they have been waiting quite a long time.
Since 1996, this group of one inch (25 millimetre) bugs, in wingless nymph form, has been a few feet underground, sucking on tree roots and biding their time. They will emerge only when the ground temperature reaches precisely 64F (almost 18C). After a few weeks up in the trees, they will die and their offspring will go underground, not to return until 2030. "It's just an amazing accomplishment," Ms Berenbaum said. "How can anyone not be impressed?"
And they will make a big racket, too. The noise all the male cicadas make when they sing for sex can drown out your own thoughts, and maybe even rival a rock concert. In 2004, Gene Kritsky, an entomologist at the College of Mount St Joseph in Cincinnati, measured cicadas at 94 decibels, saying it was so loud "you don't hear planes flying overhead".
There are ordinary cicadas that come out every year around the world, but these are different. They are called magicicadas - as in magic - and are red-eyed. And these magicicadas are seen only in the eastern half of the United States, nowhere else in the world.
There are 15 US broods that emerge every 13 or 17 years, so that nearly every year, some place is overrun. Last year it was a small area, mostly around the Blue Ridge Mountains of Virginia, West Virginia and Tennessee. Next year, two places get hit: Iowa into Illinois and Missouri; and Louisiana and Mississippi. And it is possible to live in these locations and actually never see them.
This year's invasion, Brood II, is one of the bigger ones. Several experts say that they really do not have a handle on how many cicadas are lurking underground but that 30 billion seems like a good estimate. At the Smithsonian Institution, researcher Gary Hevel thinks it may be more like one trillion. Even if it is merely 30 billion, if they were lined up head to tail, they would reach the Moon and back.