A large brood of 17-year cicadas, known as "Brood II", is set to emerge from underground this spring along the East Coast, from the Carolinas to New York. This will be the largest influx of these mainly harmless bugs since a separate group, "Brood X", ascended in 2004. Though many find them bothersome, University of Maryland entomologist describes the predicted onslaught as "spectacular" and "amazing".
The emergence could include parts or all of the New York Metropolitan area, where swarms may number as high as 1 billion bugs per square mile. John Cooley, a research scientist from the University of Connecticut, notes this brood has been seen in the past in the Bronx and might also come out in Central Park.
Expect to see them in late April or May in the South and by the latter part of May to early June in the cooler northern states.
"The timing depends on the weather," says Dan Mozgai, a cicada enthusiast from Metuchen, N.J. and founder of the website cicadamania.com. "They typically emerge when the soil temperature reaches 64 degrees."
There are at least 15 known broods of periodical cicadas that emerge every 13 or 17 years in different parts of the East, depending on the group. Some species return every summer. The bugs have only been spotted as far west as Texas and Oklahoma.
Cicadas stay alive underground, according to the Penn State University Entomology Department, by draining fluid from the roots of plants. They emerge to breed and usually only live about two to four weeks, or shorter if they are eaten as they are prey to most animals including deer, squirrels, house pets, birds, and people.
They posit no threat to humans, but females can damage small trees, such as those in fruit orchards, when they lay their eggs in branches. However, that can have a positive effect on trees by ridding them of their weaker branches. They also aid their host trees by aerating soil as they emerge, and "form a vital link in the food chain between trees and literally hundreds of carnivores and omnivores," writes Morzgai on his website.
The loud buzz they are known for, emitted by males when they are alarmed and when they are trying to attract females, can reach 90 decibals, which is as loud as a lawnmower.
Cooley runs the magicicada.org website, and requests reports from people who see cicadas this spring.
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