Like a scene from a science-fiction movie, red-eyed insects are popping upnow in freshly turned gardens, squirming beneath logs and stones and diggingtunnels as they plot their escape.
After a 17-year wait, a few cicadas are making an early break from thesubterranean world. If scientific predictions hold, the insects will appear enmasse in the Chicago area May 22.
For now, if you flip a log or stone in the Fullersburg Woods ForestPreserve in Oak Brook, you may see scores of the cicadas, still in a nymphalstage, along with even more of the half-inch holes they're digging -- some atthe end of chimney-like protrusions from the soil.
In Wilmette, Martha Hellander was moving a steppingstone in her garden lastweek and was shocked to find 17 tan-colored cicada nymphs underneath.
"It was really creepy," said Hellander, 54, who moved into the home 16years ago, one year after the last appearance of the insects that emerge onlyevery 17 years. "I sort of screamed and dropped it and then I went back,because I was curious. There were so many of them."
Some nymphs also have been seen emerging in the Wonder Lake yard of agardener volunteer for the University of Illinois Extension. That's typical,said Phil Nixon, an extension entomologist. A few cicadas always come beforethey're expected or up to a year afterward.
"There always are a handful of early emergers, and of course they're goingto be nailed by birds right off the bat," Nixon said. "There's not that many,so they're going to get picked off."
Exactly why and when the full swarm of cicadas will emerge -- in densitiesof up to 1.5 million an acre -- is one of nature's mysteries. The bestscientists can tell is it's a combination of factors including the weather,the length of the day and the ground temperature.
Using a formula based on April temperatures and projections of when thesoil will reach a temperature of 64 to 65 degrees, Gene Kritsky, anentomologist at the College of Mt. St. Joseph in Cincinnati, predicted theexact date of the emergence of the same species of cicada in Ohio three yearsago: May 14. He had set up 15 monitoring stations around Cincinnati andwatched.
"It was like clockwork," said Kritsky, one of the nation's leading cicadaexperts.
Applying that formula to northern Illinois, Kritsky says cicadas shouldemerge here in late May. But in 1990 cool weather delayed the full emergencein the Chicago area until early June.
When the time comes, the cicadas will emerge for about two weeks, saidKritsky, but a steady rain coinciding with the soil reaching the righttemperature will drive them out quicker.
"If you have a nice, good rain to soften the soil, then they'll come out indroves," he said.
The batch expected this year is called Brood XIII and its days arenumbered. Seventeen years ago they hatched as ant-sized nymphs and then grewthrough five juvenile stages about a foot underground, feeding on tree rootsand wintering below the frost line.
Before long, the inch-long nymphs will emerge, find a nearby leaf and moltto become hard-shelled, black adults. They don't bite or damage property, butthey'll make a tremendous racket as they desperately look for mates. A fewweeks later, they'll die.
Allison Lehnen, an environmental educator for the Lake County ForestPreserve District, said she's seen woodpeckers poking their beaks into theground in her Mettawa back yard and eating bugs that have been tunneling theirway to the surface.
"You could see them dig in a spot and then get one and gobble it down,"Lehnen said. "They're getting closer."
IN THE WEB EDITION
Watch the cicadas emerge at chicagotribune.com/cicadas