Brood X cicadas start to emerge across the map: What to know right now

“The only way they could get inside is accidentally flying in through an open door or window, or because they had landed on a person who then carried them inside unnoticed,” Parsons says.  

During dense emergences, females can lay enough eggs in branches to damage young trees, but the abundant egg-laying also naturally prunes trees, resulting in more flowers and fruit in the years that follow. The cicadas boast other ecological benefits as well. Periodical cicadas aerate large amounts of soil when they emerge en masse, and when they die, their decaying bodies enrich the ground with nutrients.

Here’s what you need to do to get your lawn and trees ready. 

Can pest control pros help me? 

When people call for help during cicada emergence, those in pest control are largely in the position of educating clients about why the pest pros aren’t going to show up and spray down their yard with pesticide. 

“We really want people to understand and know that pesticides are not the answer, which sounds really funny coming from a pest control company,” Frank Meek of pest control company Orkin tells my CNET colleague Erin Carson. “Pesticides are not the thing to use on this insect. They don’t work for it, and it’s a waste of product, and it’s a danger to the environment just to spray down because you’re afraid of the cicadas.”

Why do so many cicadas come out at once? 

It’s thought that by emerging in such huge numbers, enough of them can avoid predators and live on to mate — basically, strength in numbers. 

What can scientists learn from mapping cicadas? 

Some people view the mass of insects as a pesky annoyance, but others welcome it as an awe-inspiring wonder of nature. Some in the latter category even regularly travel around the US to cicada emergence areas to experience the sights and sounds and help scientists map the creatures. 

Cicada mapping helps scientists verify the periodical insects’ life cycles, as well as broods’ relationships to one another, to gain a better understanding of biodiversity, biogeography and ecology. 

A free app created at Cincinnati’s Mount St. Joseph University, called Cicada Safari and available for iOS and Android, lets citizen scientists record periodical-cicada sightings. They can also record sightings at the websites Cicada Mania and iNaturalist, a joint initiative of the California Academy of Sciences and the National Geographic Society. 

Because periodical cicadas are sensitive to climate, patterns of different broods and species reflect climatic shifts, note John Cooley and Chris Simon, professors of ecology and evolutionary biology at the University of Connecticut. 

“For example, genetic and other data from our work indicate that the 13-year species Magicicada neotredecim, which is found in the upper Mississippi Valley, formed shortly after the last glaciation,” they write in a piece for The Conversation. “As the environment warmed, 17-year cicadas in the area emerged successively, generation after generation, after 13 years underground until they were permanently shifted to a 13-year cycle.”

Because Brood X occurs four years after Brood VI and four years before Brood XIV and because the three broods are adjacent to one another in parts of their geographic ranges, cicada trackers may spot “stragglers” from other broods this year.

“From a biological perspective, four-year stragglers from either of these broods are of interest because they can cause gene flow among these broods,” the University of Connecticut explains. “From a practical perspective, four-year stragglers from any of these broods complicate mapping efforts, because populations may be difficult to assign to a brood.”  

Stragglers may confuse mapping efforts, but the university stresses that a “misleading map is worse than no map at all.”