ANIMALS
More than a trillion cicadas could emerge throughout the Midwest and Southeast of the US this spring, as the schedules of two separate broods align for the first time since 1803. Brood XIII and Brood XIX represent two distinct groups of periodical cicadas that emerge according to 17 and 13-year life cycles respectively. In a rare natural event that occurs once every 221 years, these two broods will both tunnel through the ground to the surface, starting in late April, across 16 states.
The event, known as a dual emergence, could potentially lead the two broods to interbreed. “Under just the right circumstances and with just the right number of individuals cross-breeding, you have the possibility of the creation of a new brood set to a new cycle,” said Floyd Shockley, an entomologist and collections manager at the Smithsonian National Museum of Natural History.
Periodical cicadas, which comprise seven species, spend most of their lives underground as nymphs and feed off sap that oozes from tree roots. After 13 or 17 years starved of daylight, depending on the species, the insects burrow to the surface using their front legs and transform into adults. The males vibrate membranes on the sides of their bodies to produce a song that attracts mates. Once a pair has finished mating, the females cut slits in tree branches to lay their eggs in. Adult periodical cicadas survive for three to four weeks and don’t live to see their eggs hatch roughly three weeks later. The newly hatched nymphs then drop to the ground and tunnel down into the soil to repeat the cycle.
Brood XIII, which has a 17-year cycle, and Brood XIX, which has a 13-year cycle, will overlap along a narrow band in northern Illinois and eastern Iowa. Brood XIII, also kno
