People in the eastern United States are getting a treat this spring - if you consider more cicadas than usual a treat. Five different cicada broods have emerged instead of the one that was expected.
Brood IX has appeared more or less on schedule in parts of Virginia, West Virginia and North Carolina. Brood XIX has shown up four years early in 10 states. Members of Brood X are popping up a year before they usually do, with appearances in D.C., Tennessee, and Southwest Ohio. Chicago is seeing Brood XIII cicadas, four years early. There's one latecomer too: Brood V has been found in Eastern Ohio.
"So far, we're looking at over a dozen states this year recording these off-cycle emergences," says Mount Saint Joe Dean of Behavioral and Natural Studies Gene Kritsky. "The only continent-wide impact that we see that could be possible is increasing temperatures."
He says the trees cicadas feed on are responding to warmer temperatures and the insects are following along.
Kritsky says on average, cicadas are coming out of the ground two to three weeks earlier than they did in the 1940s. He says the first reported emergence this year was in April, a month and a half earlier than expected.
Cicadas are an important indicator of the health of forests, Kritsky says. "They tell us about land use. Indiana, for example, in the 19th century, had cicadas in every county but one. And now there's almost 40 counties they no longer occur in."
An app released last year is helping Kritsky and other scientists track the early birds and the stragglers. Nearly 12,000 people have downloaded Cicada Safari this year. The free app allows them to send researchers the location of cicada sightings and pictures. Kritsky says the 2.0 version includes 10-second video clips, which means researchers can hear the calls of the cicada. "There are three different species and their calls are very distinct," he says.
Kritsky doesn't expect these off-schedule emergences to affect the insects or the study of entomology. "The only time that it would have a major impact is if the numbers emerging early was great enough to overwhelm predators and then start a self-reproducing population," he says.