Patches of the East Coast are buzzing with the return of the 17-year cicadas. They’re carpeting spots from Georgia to Connecticut, and filling the air with a 7 kHz mating buzz.They are expected to be seen in late May to early June this year.
Cicadas are large insects, about an inch and a half long, with black bodies, red eyes and delicate wings. There are far too many to count. You see them everywhere – on the sidewalk, on the trees, on the porch, on the street.
Cicadas of the same life cycle are known collectively as a single “brood”. There are 12 broods of 17-year cicadas. As a result, it is possible to find cicadas in almost any year by traveling to the appropriate location. The group expected in the eastern United States this spring, known as Brood 2, are the offspring of cicadas last seen in 1996.
Usually in early to mid-May, the cicada nymphs crawl out of the ground, onto trees and shed their skins. The males sing very loudly to attract female mates. The females lay their eggs in the branches of trees. The nymphs hatch and burrow several inches underground. The above ground cycle lasts less than four weeks. Beginning in mid-June, the adults all die. Male cicadas die soon after mating. Females lay 400 to 600 eggs before they die.
Fortunately, Cidadas don’t bite or sting so they’re not harmful to people or pets. They generally leave no lasting damage, except possibly to young trees and shrubs. They are annoying to most, though some people find them and their unique life cycle to be fascinating.
Magicicadas cicadas have 13-year or 17-year life cycles – the longest known for an insect. They spend virtually their entire lives beneath the ground, then emerge, become adults, and breed only to die within a few weeks.
Why 17 year cycles?
Three and 17 are prime numbers. Perhaps this prime time emergence was an evolutionary development enabling them to outwit parasites. That is, parasites life cycles are much shorter, generally a few years. Because a prime number is not divisible by any number except itself and 1, it would be very difficult for a parasite to try to match its own life-cycle emergence with that of the periodic cicada. Thus, if a parasite species were dependent on the cicada, it is likely that the parasite species would become extinct.
By emerging in such high numbers (there can be as many as hundreds of thousands of cicadas emerging simultaneously in a single acre), it is almost impossible for predators of the periodic cicada to be able to eat them all, thus enabling its species to survive.
These cicadas live 13 or 17 years about 6 to 18 inches underground as nymphs feeding on tree roots. In the spring of their emergence, they begin tunneling exit holes, of about 1/2 inch in diameter, to the surface. When the soil temperature in the exit hole reaches 64 degrees F, the nymphs emerge from the holes at sunset, and climb up trees or any nearby structure. At night, the skin is shed and the adult emerges, spending just under a week harboring to enable their skin to harden and become fully adult.
Although southern cicadas tend to emerge sooner than northern cicadas, due to the warmer temperatures, all cicadas in a region will emerge at the same time. Additionally, the periodical cicadas of a brood will tend to emerge at roughly the same time of year every cycle, with some variation for temperature.
Cicadas won’t come out unless it’s warm (ground temperature must be over 46 degrees F.). This Memorial Day weekend, which is forecast to have nocturnal temperatures below freezing in Pennsylvania, does not classify as “warm.” Cicada emergence may be delayed or less than expected.
You can help track the cicada showing here. Cicada Tracker by Radiolab is gathering data on this year’s cicada emergence timeline. Data gathered will help scientists track and follow cicada populations over their shot life cycle and long dormancy. Click here for details of this great school project and or more cicada information.
Follow all the news about Green Living, Pets, Education and Child Health by subscribing to my articles. Click on the “Subscribe” button, or here: http://usedview.com/user-bmader.