With uncanny mathematical precision, and with sex on their minds, millions of red-eyed cicadas that last saw daylight in 1987 are poised just beneath the Maryland soil, raring to wriggle out, raise hell, make love and die, carpeting the ground with rotting carcasses.
"Oh, my God - the smell," said University of Maryland biologist Holly Menninger. "We're talking ankle deep in cicada carcasses" in some places.
The insects mounting this invasion are periodical cicadas, which burst forth in plaguelike proportions every 13 or 17 years, depending on the species and location.
This year, most of Maryland from Garrett County to Cecil County, excluding most of the Eastern Shore and Southern Maryland, will greet Brood X (10), the biggest of the 15 periodical clans.
"All heck is about to break loose here," said University of Maryland entomologist Mike Raupp, who is tracking the bugs from Baltimore to College Park as they tunnel toward the surface.
"They're there, happy and smiling in their holes," he said. "In every place I've been, I've found moderate to heavy populations. ... It looks like a bumper crop to me."
Brood X emerges every 17 years in nine Eastern states from Indiana to New Jersey. Often mistaken for locusts (a type of grasshopper), periodical cicadas spend all but a few weeks of their lives underground, sucking nutrients from the roots of the trees where they were born.
When the time to emerge nears, the nymphs dig pencil-size escape shafts to the surface, sometimes capped by mud piles until it's time to crawl out.
Appearing with militarylike coordination, their arrival can be dramatic: In wooded areas with undisturbed soil, 200 nymphs can squirm up from a single square yard. An acre can cough up 1 1/2 million.
Once they reach daylight, the nymphs crawl up a tree trunk, a screen door or other vertical perch and shed their skins, revealing winged adults.
Fluttering into the trees, they commence cicada karaoke. Males croon to females in a courting ritual that can drive homeowners batty and crank hand-held decibel meters to near-rock-concert peaks.
Brevisana brevis, the African cicada, is the loudest recorded insect on Earth at 106.7 decibels. But even Maryland's garden-variety Magicicada septendecim produces a racket that can overpower a rumbling lawn mower.
While scientists have only recently begun to unravel the cicada's mysteries, the insect's behavior has fascinated observers since North America was settled.
Recorded in 1633
As entomologist Gene Kritsky points out in his forthcoming book, Periodical Cicadas: The Plague and The Puzzle, the first recorded emergence was quaintly chronicled in 1633 by William Bradford, governor of Plymouth Colony:
"There was such a quantity of a great sort of flies like for bigness to wasps or bumblebees, which came out of holes in the ground and replenished all the woods, and ate the green things, and made such a constant yelling noise as made all the woods ring of them, ready to deaf the hearers. They have not, by the English been heard or seen before or since."
Commenting on the 1715 emergence of Brood X in Philadelphia, Swedish clergyman Andreas Sandel noted curiously that "people split them open and eat them." More about that later.
Entomologists have found three species of 17-year cicadas within Brood X, each with a slightly different size, coloration, mating behavior and habitat preference. The males' songs differ, too, because they must attract females of their species.
One of the biggest cicada mysteries remains: How do bug brains keep track of the years?
Researchers suspect the cicadas can detect seasonal changes in the sugar or protein content of the tree sap they consume.
In experiments that artificially shortened seasonal cycles of light and temperature for plants and insects, the cicadas emerged after 17 cycles, even when each was just four months long. "How they're counting to 17, that's the totally unknown question," said Indiana University biologist Keith Clay.
However they figure it out, the Brood X nymphs have crawled to within a few inches of the surface, waiting for warmer weather. "Once it hits about 64 degrees 8 to 10 inches deep, that's the signal to come out," Clay said. When they do, "it's pretty synchronized, mostly all in one night."
Cicadas aren't the only ones counting: Officials at Boys' Latin School in North Baltimore tallied the years since 1987 and decided to move this year's June 5 commencement indoors, a reluctant break with the traditional celebration on the school's Lake Avenue lawn.
Cicadas also forced the school's 1987 commencement indoors.
"It wasn't just the fact that they were flying around," said public relations director Leslie Heubeck. "It was the noise they generated. Even though we have a PA system, they were loud enough that we were worried."
And with cicadas, there is always the "ick" factor.
"I don't speak for all women," Heubeck said, "but the cicadas scare me to death. I remember 17 years ago not wanting to be outside. ... I know they don't [bite], but they're really very ugly bugs. And they're big."
Change of plans
Johns Hopkins surgical resident Frank Lin and his fiancee were planning a May 30 wedding in an elm grove at the Audubon Society's Woodend Mansion in Chevy Chase. That is, until a fellow surgeon described a June 1987 wedding with cicadas that flew into guests' hair and landed in the food. "He said it was a day you would definitely never forget," Lin said.
Lin and his fiancee have postponed their nuptials to October.
For most of us, there is no way to avoid the ancient and inexorable spectacle - short of bugging out-of-state for a month.
The 1987 appearance of Brood X began about May 15. By the first week in June, the males were in full song. Noise levels in Milford, Rodgers Forge and were measured at 80 decibels in the afternoon. That's nearly as loud as a heavy truck passing on the Beltway and well above the state's residential limit of 65 decibels.
Pedestrians complained that females flew like drunken sailors, bouncing off walls and windshields, and dropping onto car seats and hairdos. Homeowners covered lawn furniture. Some draped vulnerable saplings in cheesecloth.
This year, panicked gardeners have been calling Carrie Engel, greenhouse manager at Valley View Farms in Cockeysville.
"I think a lot of them are misinformed and think cicadas are much like locusts and chew everything up," she said.
In fact, they're not locusts, and they don't chew anything. Their feeding - sucking on tender plant parts for nutrients and moisture - causes no significant damage. Aside from the smelly mess when they die en masse, their only real impact will be some tree "flagging" - a dieback of leaves as the females slice the bark of small branches to lay their eggs. For the most part, it doesn't hurt the trees.
"It's just like a natural pruning," Engel said.
Still, Engel recalled her own encounter with Brood X in 1970, after a high school softball game, when the girls returned to a bus that was parked under some shade trees - with the windows open. "By the time we got back in the bus, it was full of them," she said. "For a bunch of teen-age girls, it wasn't a pleasant experience."
The ick factor again.
Cicadas don't bother house pets - quite the opposite. Cats and dogs often find the surfeit of clumsy, crunchy insects the irresistible equivalent of an all-you-can-eat buffet. They just don't know when to stop eating.
Dr. Kim Hammond, a veterinarian at the Falls Road Animal Hospital, remembers the 1987 invasion. "The dogs got into huge piles of them, got sick and threw up," he said. "They don't even chew - they inhale."
Cicadas are safe for human consumption, in moderation - provided they haven't been exposed to insecticide (which is not recommended). Kritsky, who has eaten cicada nymphs "Cajun-style, stir-fried and raw in salads," likens the taste to "cold canned asparagus." Low in carbs, the nymphs are Atkins-diet friendly, he says.
Ick factor aside, many will find the spectacle fascinating. "This is gonna be active, raw nature," Raupp said. "They're gonna be mating, flying, crashing into buildings, running away from birds. They're gonna be eaten, having sex, laying eggs, falling out of treetops. And people will have the opportunity to witness everything that happens in biology."
The Brood X invasion is the largest insect emergence in the world. Although its precise boundaries are fuzzy, the heaviest populations are in Indiana, extending into southern Michigan and western Ohio.
Most of Maryland lies in a second zone that extends from northern New Jersey, across the southeastern half of Pennsylvania, into Delaware, Northern Virginia and eastern West Virginia. A third segment extends from northern Georgia to eastern Tennessee and western North Carolina.
Maryland is host for other broods too. The largest is Brood II, which appeared in 1996, in Calvert and St. Mary's counties.
Periodical cicadas in North America have been in retreat for centuries as agriculture and development have destroyed their wooded rural habitat.
But the future might not be entirely bleak. In fact, Clay said, "a central theme of our research is that humans have modified the landscape in a way that may make it more conducive to higher populations of cicadas and bigger outbreaks."
Suburban developers are converting farmland to parklike suburbs with grass and scattered trees, "which is really excellent habitat for cicadas," Clay said. Ditto for golf courses.
Meanwhile, in undeveloped rural areas, small farms are being abandoned, so forests are returning. The cicadas will likely follow, although "it would be a slow encroachment," Clay said.
Not everyone will welcome them. Dr. John R. Lion, a Baltimore psychiatrist, noted in 1987 that the cicadas' appearance, brief frenzy and death provoked anxiety, revulsion and even suicidal thoughts in some patients.
In a column for The Sun, he concluded that "these weird little bug-eyed bugs ... actually stirred up some buried panic about mortality, and they pushed buttons within us that made us flee in horror, or stare in wonder, or duck and hide. Was our existence to be equally brief and puny?"