Periodical cicadas off-schedule in Kansas
An insect anomaly has occurred in eastern Kansas. Periodical cicadas--the kind that stay buried for 13 or 17 years before emerging as adults--deviated this year from their schedule of precisely timed mass appearances.
Historically, Kansas is home to Brood IV periodical cicadas, which arrive every 17 years. Their next scheduled emergence is in 2015, said Bob Bauernfeind, entomologist with K-State Research and Extension.
"This year's periodicals could be stragglers. That's the term used to describe periodical cicadas that unpredictably emerge out of sync, before or after their scheduled time," Bauernfeind said. "Getting a few stragglers a year early or late isn't all that uncommon. But, our limited records of stragglers' arriving four years early suggest they're likely to be more numerous, and we didn't see that in Kansas this year."
Brood XIX cicadas are the only group with 2011 on their schedule. In geographic terms, they're the largest, so they're sometimes called the "great southern cicada brood." They emerge every 13 years in the Midwest from Iowa, through Missouri, and down into Oklahoma and Arkansas. From there, they extend across the South to Georgia and up the East Coast into Maryland.
"Could this year's Kansas periodicals have been Brood XIX members--either out of place or expanding territory? We won't have clear proof of that until Brood XIX emerges again in 2024. At that time, any periodicals in Kansas will have to be XIXers. They couldn't be Brood IV stragglers--even the four-year kind--because after 2015, the next Brood IV emergence will be in 2032," he said.
Periodical cicadas only live in eastern North America. Their genus name--Magicicada--sounds as mysterious as their lock-step behavior is to scientists. The last of their seven known species was just discovered in 1998.
All seven have black bodies, large wings with orange veins, and big red eyes. Sometimes the easiest way to tell them apart is by the males' species-specific "mating song." At about 1.5 inches long, they're a bit smaller than the "annual" or "dogday" cicadas that appear every year in midsummer.
Periodicals usually emerge in late May to early June. The exact timing seems to depend on soil temperatures.
The many years that periodical cicada nymphs spend in the soil, sucking on tiny roots, make the Magicicada one of the longest-lived insects on Earth. They're also related to the world's loudest insect: the male African cicada. But, periodical cicadas' reputation for being raucous and noisy relates to their emerging in astounding numbers--seemingly overnight. Populations can range from about 10,000 to as high as 1.5 million per acre.
Having more than one brood emerge in Kansas at regular intervals wouldn't be the first case of its kind. The four species with 13-year life cycles generally make their grand appearances in the South and/or Midwest. The three species with 17-year cycles have a more northern distribution. And, some centrally located states are home to both, the entomologist said.
North America has more broods than species of periodical cicadas because a single species can include large, but scattered populations. In turn, those same-species groups can emerge during different years, because when periodicals emerge depends on where they live, Bauernfeind said. Complicating things further, various species' "territories" can overlap. So, this year's Brood XIX emergence across the South could have included several species--all emerging, singing and mating in unison.
That's why species rarely comes up outside of scientific discussions. Most people refer to periodical cicadas by their Roman numeral brood "category," which identifies a group of cicadas that always emerge in the same year and place, after spending the same number of years underground. A chart of those categories, their nearby years of appearance, and general by-state region of emergence is available online at www.magicicada.org/about/brood_pages/broods.php.