The last time this many cicadas emerged Thomas Jefferson was president
Trillions of evolution鈥檚 bizarro wonders, red-eyed periodical cicadas that have pumps in their heads and jet-like muscles in their rears, are about to emerge in numbers not seen in decades and possibly centuries.
Crawling out from underground every 13 or 17 years, with a collective song as loud as jet engines, the periodical cicadas are nature鈥檚 kings of the calendar.
These black bugs with bulging eyes differ from their greener-tinged cousins that come out annually. They stay buried year after year, until they surface and take over a landscape, covering houses with shed exoskeletons and making the ground crunchy.
This spring, an unusual cicada double dose is about to invade a couple parts of the United States in what University of Connecticut聽cicada聽expert John Cooley called 鈥渃icada-geddon.鈥� The last time these two broods came out together in 1803 Thomas Jefferson, who wrote about cicadas in聽his Garden Book聽but mistakenly called them locusts, was president.
鈥淧eriodic cicadas don鈥檛 do subtle,鈥� Mr. Cooley said.
An alien-like species is coming to say hello
If you鈥檙e fascinated by the upcoming聽solar eclipse,聽the cicadas are weirder and bigger, said Georgia Tech biophysicist Saad Bhamla.
鈥淲e鈥檝e got trillions of these amazing living organisms come out of the Earth, climb up on trees and it鈥檚 just a unique experience, a sight to behold,鈥� Mr. Bhamla said. 鈥淚t鈥檚 like an entire alien species living underneath our feet and then some prime number years they come out to say hello.鈥�
At times mistaken for voracious and unrelated locusts, periodical cicadas are more annoying rather than causing biblical economic damage. They can hurt young trees and some fruit crops, but it鈥檚 not widespread and can be prevented.
The largest geographic brood in the nation 鈥撀燾alled Brood XIX聽and coming out every 13 years 鈥撀爄s about to march through the Southeast, having already created countless boreholes in the red Georgia clay. It鈥檚 a sure sign of the coming cicada occupation. They emerge when the ground warms to 64 degrees (17.8 degrees Celsius), which is happening earlier than it used to because of聽climate change, entomologists said. The bugs are brown at first but darken as they mature.
Soon after the insects appear in large numbers in Georgia and the rest of the Southeast, cicada cousins that come out every 17 years will inundate Illinois. They are聽Brood XIII.
鈥淵ou鈥檝e got one very widely distributed brood in Brood XIX, but you have a very dense historically abundant brood in the Midwest, your Brood XIII,鈥� said University of Maryland entomologist Mike Raupp.
鈥淎nd when you put those two together 鈥� you would have more than anywhere else any other time,鈥� University of Maryland entomologist Paula Shrewsbury said.
Think trillions, maybe even quadrillions
These hideaway cicadas are found only in the eastern United States and a few tiny other places. There are 15 different broods that聽come out every few years, on 17- and 13-year cycles. These two broods may actually overlap 鈥撀燽ut probably not interbreed 鈥撀爄n a small area near central Illinois, entomologists said.
The numbers that will come out this year 鈥撀燼veraging around 1 million per acre over hundreds of millions of acres across 16 states 鈥撀燼re mind-boggling. Easily hundreds of trillions, maybe quadrillions, Mr. Cooley said.
An even bigger adjacent joint emergence will be when the two largest broods, XIX and XIV, come out together in 2076, Mr. Cooley said: 鈥淭hat is the cicada-palooza.鈥�
The origin of some of the astronomical cicada numbers can likely be traced to evolution, Mr. Cooley and several other entomologists said. Fat, slow, and tasty, periodical cicadas make ideal meals for birds, said Mr. Raupp, who eats them himself. (His school put out a聽cicada cookbook called 鈥淐icada-Licious.鈥�) But there are too many for them to be eaten to extinction, he said.
鈥淏irds everywhere will feast. Their bellies will be full and once again the cicadas will emerge triumphant,鈥� Mr. Raupp said.
The other way cicadas use numbers, or math, is in their cycles. They stay underground either 13 or 17 years, both prime numbers. Those big and odd numbers are likely an evolutionary trick to keep predators from relying on a predictable emergence.
The cicadas can cause problems for young trees and nurseries when their mating and nesting weighs down and breaks branches, Ms. Shrewsbury said.
Periodical cicadas look for vegetation surrounding mature trees, where they can mate and lay eggs and then go underground to feast on the roots, said Mount St. Joseph University biologist Gene Kritsky, a cicada expert who wrote聽a book on this year鈥檚 dual emergence. That makes American suburbia 鈥減eriodical cicada heaven,鈥� he said.
Whole trees will be screaming
It can be hard on the eardrums when all those cicadas get together in those trees and start chorusing. It鈥檚 like a singles bar with the males singing to attract mates, with each species having its own mating call.
鈥淭he whole tree is screaming,鈥� said Mr. Kritsky, who created a聽Cicada Safari app聽to track where the cicadas are.
Mr. Cooley takes hearing protection because it can get so intense.
鈥淚t鈥檚 up in the 110 decibel range,鈥� Mr. Cooley said. 鈥淚t鈥檇 be like putting your head next to a jet. It is painful.鈥�
The courtship is something to watch, Mr. Kritsky imitated the male singing 鈥渇faairro (his pitch rising), ffaairro.鈥�
鈥淪he flicks her wings,鈥� Mr. Kritsky narrated in a play-by-play. 鈥淗e moves closer. He sings. She flicks her wings. When he gets really close, he doesn鈥檛 have a gap, he鈥檒l go ffaairro, ffaairro, ffaairro, fffaairo.鈥�
Then the mating is consummated, with the female laying eggs in a groove in a tree branch. The聽cicada nymph will fall to the ground, then dig underground to get to the roots of a tree.
Cicadas are strange in that they feed on the tree鈥檚 xylem, which carry water and some nutrients. The pressure inside the xylem is lower than outside, but a pump in the cicada鈥檚 head allows the bug to get fluid that it otherwise wouldn鈥檛 be able to get out of the tree, said Carrie Deans, a University of Alabama Huntsville entomologist.
The cicada gets so much fluid that it has a lot of liquid waste to get rid of. It does so thanks to a special muscle that creates a jet of urine that flows faster than in most any other animal, said Georgia Tech鈥檚 Mr. Bhamla.
In Macon, Georgia, T.J. Rauls was planting roses and holly this week when he came across a cicada while digging. A neighbor had already posted an image of an early-emerging critter.
Mr. Rauls named his own bug 鈥淏obby鈥� and said he鈥檚 looking forward to more to come.
鈥淚 think it will be an exciting thing,鈥� Mr. Rauls said. 鈥淚t will be bewildering with all their noises.鈥�
This story was reported by The Associated Press.
