At first, the noise pulsing from the drooping elm tree boughs seemed to be coming from the power lines erected nearby. Like a surging electrical current, the sound fizzed to a crescendo on the ears before receding slightly, only to build up again to a loud, vibrating whirr.
It was only on the approach to the tree, as desiccated bodies crunched underfoot and small but sturdy creatures sporting wings and orange eyes suddenly clung on to our calf muscles, that it became apparent what was causing such a huge racket: millions of cicadas had just erupted from the earth.
One of the world’s great natural spectacles is under way in the eastern US, stretching from the deep south to upstate New York. Trillions of periodic cicadas are emerging en masse from a 17-year dormancy underground to clamber up trees, let out calls that rattle the eardrums, furiously mate and hand off the next leg of an extraordinary evolutionary cycle to their offspring.
“This is a spectacular chorus, just incredible” said Michael Raupp, an entomologist at the University of Maryland who happily lets one of the insects crawl up his cheek. We are beside a small stand of trees in Columbia, Maryland, a leafy commuter suburb near Washington. It’s swelteringly hot, a pleasing temperature for the screeching cicadas.
The scene is not only raucous – a swarm of cicadas can produce a sound that reaches around 100 decibels, louder than a revving motorcycle – but also grisly. Cicadas flail around in a stupor on their backs, some lie squashed, others are picked off by a red-shouldered hawk that is shoveling insects into the gaping maws of two ravenous chicks in a nearby nest. The amber-colored exoskeletons shed by the cicadas litter the seething ground and pockmark the trunk and branches of the elm tree.
Millions, perhaps billions, of the insects don’t even make it to this point. In the past 17 years, much of the ground containing cicadas has been paved over for roads and driveways and shopping malls. Their foot-deep refuges became tombs, even before the cicadas could run the gauntlet of the overland.
Raupp scrabbled in the dirt to show the small holes where more fortunate cicadas managed to tunnel to daylight using their shovel-like front legs. At first, the nymphs are a ghostly white before shedding their skins and developing a hardened exoskeleton. The task is to then ascend a tree, with the males creating what Raupp calls a “big boy band” of noise to attract females for mating.
Some broods emerge in 13-year cycles and others in 17-year periods and while there is no definitive explanation for this phenomenon, many entomologists believe the cicadas have developed this as a defensive move against predators. No foe – squirrel, hawk or raccoon – will live the 17 years to lie in wait, with the massed synchronized numbers always allowing enough survivors to breed and kickstart the next generation. Underground, the cicadas either track the passing years from the burst in plant activity each spring or rely upon some sort of internal clock, their own circadian rhythm.
Both males and females are drawn to the males with the loudest calls, again to build strength in numbers. One of the elm trees is dominated by cassinii, the cicada species that produces the juddering electrical circuit noise that, when up close, sounds like the clicking of a million tiny castanets. But amid the heaving mass of bodies there is also a stray septendecim, a different type of cicada that makes a more ethereal “woo-hoo” call.
We hunt for the stray noise until Raupp finds the caller and squeezes him gently between thumb and forefinger, causing the cicada to let out a squeak similar to the sound of shoes on a basketball court. Visible on the cicada is its tymbal, a membrane on the drum-like abdomen that is vibrated to make its distinctive noise. “The males are singing their brains out to bring as many people to the party as they can,” said Raupp, as he looked at the rogue septendecim. “But if you want to hook up, you better be in the right bar.”
If a female takes a shine to a male’s call, she will flick her wings to signal mating can occur. Females will then cut a slit into a branch to deposit a clutch of 20 to 30 eggs via their ovipositors, a tubular egg-laying organ. Once hatched, these nymphs will then drop to the soil to bury themselves to begin the next stanza in the cicadas’ story.
But even the carnal stage is fraught with danger. We spot one cicada slowly ambling up the tree trunk with a noticeably white rear end – a sign it has been infected by a psychedelic fungus called Massospora, which produces an amphetamine in the insects that causes their bottoms to fall off before they mate uncontrollably with both male and female cicadas, spreading the fungus further.
Raupp, who is wearing a T-shirt with a giant cicada emblazoned upon it, is a vocal proponent of the species, once seasoning a few cicadas, placing them on a skewer and smuggling them into his carry-on baggage in order to travel to California and appear on Jay Leno’s late night talkshow. The host gamely ate the crunchy delicacy but Russell Crowe, a guest on the TV show, demurred. “He whispered to me ‘there’s no way I’m eating that, mate’,” Raupp recalled. “I like them, they’ve got a nutty sort of flavor. Leno said they tasted better than Cheetos.”
Many people share Crowe’s antipathy, however. Raupp said a friend quizzed him on when the cicadas were emerging so that he could book a lengthy holiday to Idaho to escape their arrival. A woman in Ohio has created a body shield made of shower curtains to avoid any contact with them. Police in Georgia have begged people to stop calling 911 to report the loud noise the cicadas make. A CNN newsreader, reporting how a Maryland company was selling cicadas dipped in chocolate, broke off to admit “I’m so sick to my stomach reading this.”
This reaction can be understandable when dealing with a creature measuring two inches long that resembles a cockroach with the startling addition of orange eyes. “They don’t bite or sting you, there’s nothing to fear from them,” said Raupp, as a cadre of cicadas crawled up his leg. “But some people are phobic and I take that seriously. To have thousands of cicadas emerge at once around you can be traumatic.”
The cicadas would have more well-founded fears of us, however. The insects typically wait for soils to reach 64F to emerge, a level of warmth that is arriving several weeks earlier in the year than it was in the 1970s due to global heating, climate scientists have said. Their range is also edging northwards as their environment heats up, pushing them to an unknown fate.
The rapid development of their habitat, meanwhile, has already wiped out several broods in the US. Even if all of these risks are avoided, cicadas’ stars are destined to burn brightly but quickly – once free from their 17-year dormancy, they will all be dead within a month once their reproductive goals are met.
“It’s a changing planet and it will affect cicadas like everything else,” said Raupp. “But their lineage goes back several million years and perhaps they will adapt. They really are amazing things.”