After 17 Years, Billions of Cicadas Are Ready to Emerge

By Carl Engelking | April 18, 2016 5:32 pm

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Summer is going to be a little noisier this year on the East Coast.

Once the soil temperatures rise sufficiently, billions of cicadas are expected to emerge after spending 17 years underground. The soon-to-emerge cicadas were born in 1999 and spent the years feasting on secretions from plant roots. After toiling in the dirt for close to two decades, the cicadas will climb a tree, shed their nymphal shell, and proceed to get dirty — in the figurative sense.

Locations That Will Be Abuzz

The batch of 17-year cicadas set to surface in April or May, called Brood V, is comprised of three different species: Magicicada cassinii, Magicicada septendecim and Magicicada septendecula. They’ll start popping out of the soil when temperatures 8 inches beneath the surface reach 64 degrees Fahrenheit, which is expected to occur by May or late in April. There are 15 different cicada broods, and the designations are based on the calendar year in which they emerge. Brood VI, for example, will emerge in 2017 in parts of Georgia, North Carolina and South Carolina.

You can expect to hear Brood V cicadas in parts of Maryland, New York, Ohio, Pennsylvania, Virginia and West Virginia, according to Cicadamania.com. The website has compiled detailed, county-by-county information to find ideal emergence locations.

Getting Busy

After spending 17 years in the soil, life for a cicada moves into overdrive. Adults live just two to four weeks after they emerge — most of that time is spent mating. The loud buzzing you hear during a cicada invasion is the chorus of males attempting to sing a seducing song to a female.

The males “sing” their song with specialized noisemakers, called tymbals, which are structures of the exoskeleton located on both sides of their abdominal region. Males produce sound by flexing and relaxing muscles attached to their tymbals.

After cicadas mate, females lay hundreds of rice-sized eggs in tree branches. They’ll hatch a few weeks later and head underground, which will serve as their home until 2033.

Why a Cycle?

Species of cicadas emerge on 17- and 13-year cycles, and scientists believe this cyclical strategy evolved as a way to overwhelm predators with shear numbers. When billions upon billions of bugs take over a small area, local birds can only eat so many. Therefore, a large number of cicadas survive to spread their seed.

However, there’s a mystery here: populations of birds that eat insects are typically on the decline before an emergence event. Two years after the cicadas emerge, the bird populations boom. According to researchers’ theory, cicadas might be modulating bird populations through unknown mechanisms.

Cicada emergence events always occur in prime numbers. That may reduce their chances of predation, since most predators have lifespan cycles of roughly 2 to 5 years. Emerging every 13 or 17 years might reduce the odds that predators will be experiencing a surge in population during emergence years.

And, by the way, every so often 13-year and 17-year brood emergence events occur at the same time in overlapping territories. The next simultaneous emergence event will occur in Missouri in 2219.

CATEGORIZED UNDER: Living World, top posts
MORE ABOUT: unusual organisms
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  • Justin Waters

    I hear and see them every year. The article doesn’t say, but I suppose this year will have more than usual. The article speaks of modulating cicada breeding cycles based around bird cycles through “unknown mechanisms.” It seems the mechanism is for cicadas to emerge every year, and the year that has the least predators is the year that will have established the largest cicada brood.

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    Aristotle, Historia Animalium 556b 1.5ff, cicadas are yummy. Pliny of Rome, Naturalis Historia XI : 26, Athenaeus of Alexandria Deipnosophistoi IV p. 133b, Aelian Historiae Animalium XII : 6. Let us feed the professionally deserving with Nature’s abundant renewable resource historic singing bounty while we suffer the terrible travails of artificially inseminated corn-fed ribeye fouled by antibiotics, hormones, and obscene abattoirs.

  • OWilson

    It is refreshing to read an article that discusses the natural rise and fall of species populations, without invoking the obligatory reference to “climate change”.

    But there is quite lot of detailed scientific research in this area, of which the website source for this article seems to be unaware.

    There are algorithms that have evolved that shed light on these optimal emergent years, based on 7, 11, and 13 intervals, that are truly amazing, but not necessarily “mysterious”.

    • Nate

      I don’t think the mystery is the cycle times, thats pretty well understood as a way to limit predation. I understand it as: it is a mystery that predator populations are declining instead of holding constant, or even gearing up for an abundance in food sources, and then booming after the fact. There may be some subtle mechanism at play

      • OWilson

        I agree.

        It could be considered remarkably complicated, given the multiple variables at play, weather, predators, temperatures, prey, range, and not least the legacy “memory” from that last cycle.

        But at the same time, there is a general symmetry to it and a correcting feedback mechanism that comes in to play.

        Nature, it seems has evolved some simplifying algorithms, to make it all work.

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