What's That Buzzzzz?
They are not locusts. They are not harmful. They have no interest in us or our crops. And yes, they are LOUD.
After hanging around underground for 17 years, billions of flying bugs known as cicadas are due to sweep over the East Coast starting sometime in mid April through end of May.
Entomologists are excited. This particular group of cicadas haven't surfaced since 1999. There are 14 broods that emerge in different regions on 17-year cycles.
Meet The Cicada
Cicadas belong to the genus "Magicicada" and there are seven species in this genus. A genus is a grouping of animals with certain characteristics that is distinctly different from any other group of creatures. Of the seven species, three are 17-year cicadas and four are 13-year cicadas. You must be wondering what on earth we talking about -- 17-year, 13-year?
Well, these "years" refer to their life-cycle. Here's how it works: Once every 13 or 17 years, cicadas mate, lay eggs and die. The next time the new brood mates is -- yeah, you guessed it -- 13 or 17 years later, depending on which species it belongs to!
Life Cycle Of 17 Years
The year is 1996. The temperature in the soil about 20-30 cm (about 8 inches to a foot) below the ground is just about right at about 20 degrees Celsius or 64 degrees Fahrenheit. Cicadas have buried themselves there, with the mouths stuck to roots of trees, sucking sap and growing.
Finally, about 17 years after burying themselves, they start constructing an exit tunnel. They are preparing for the "mass cicada emergence." And then, in 2013, they are ready to come out -- billions of them. Called the "Brood II", they come out, shed the last layer of exoskeleton (the hard outer covering on most insects), inflate their wings and get ready to fly.
The roar and buzz then begins -- as the males furiously vibrate membranes in their abdomens to make the loud droning sound. They are doing this to attract a female. Then they mate and each female lays up to 600 eggs in slits in twigs. After about 3 months, the eggs hatch and the newborn "nymphs" fall to the ground, bury themselves for another 17 years -- sucking sap and growing. The adults die after mating.
Why So Long?
Why does this 17 year cycle happen? Scientists suspect it is nature's way of "shock and awe" where the cicada numbers are just too many at one time for all to get eaten up! So the cicadas are "overwhelming" predators who love them -- turkeys, raccoons, skunks, squirrels -- so a large number of them survive to mate. Ingenious, huh?
The Noise, Oh It's Deafening!
Oh and what of that NOISE? The buzzing sounds like a chain saw or an approaching lawn mower. The 17-year cicadas singing together have been measured at 100 decibels (decibel is a unit of sound -- how loud something is). In contrast, a subway train is at 95 decibels and a power mower is at about 107 decibels. So the noise the cicadas make is loud. This does irritate the neighborhoods where these creatures emerge, but, rest assured, it will all be gone in a few weeks -- until 2030!
Side notes: Did You Know?
Cicadas are considered a delicacy in many parts of the world, as the insects are low in fat and high in protein!
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|Title Annotation:||Our Earth; cicadas|
|Date:||Apr 24, 2016|
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