A massive brood of periodical cicadas will emerge soon across the eastern United States, with the notoriously raucous springtime insects due for their 2025 appearance.
Known for their buzzing hordes and ability to rapidly infiltrate the environments where they show up, cicadas are expected to swarm parts of Kentucky and Tennessee this year, while arriving in smaller quantities in various places along the East Coast, from Massachusetts and New York down to western Georgia.
Here’s what to know about the infamous creatures.
What are periodical cicadas?
Periodical cicadas are moderately sized bugs with red eyes and translucent wings, usually measuring about an inch long with a wider wingspan. They are sometimes mistakenly associated with locusts, like grasshoppers, but cicadas are actually an entirely different sort of insect, part of the same family as stink bugs and bedbugs.
The synchronized behavior of periodical cicadas is their most defining characteristic. Compared with annual cicadas, which appear in generally modest amounts each summer, periodical cicadas emerge in the spring and essentially rise from the ground in unison, in either 13-year or 17-year intervals. Cicadas that emerge on the same schedule are called a brood, and each is labeled using Roman numerals.
This year, the group belongs to Brood XIV, the second-largest brood of periodical cicadas known to scientists, according to the University of Connecticut. Researchers with the university’s Cicada Project note that, while they cannot technically know with certainty where a particular brood is going to emerge next, its last known locations during previous emergence events usually provide valuable insights. Because periodical cicadas typically lay their eggs in or near the areas where they’ve just emerged, the next generation of broods tend to emerge themselves in similar places.
Cicada map predicts where they will emerge in 2025
Based on University of Connecticut research, CBS News’ data team created an interactive map that charts the expected spread of Brood XIV, which last arose 17 years ago and is the only brood emerging in 2025.
The map shows the cicadas primarily concentrated in Kentucky and Tennessee, in addition to parts of Georgia, Illinois, Indiana, North Carolina, Virginia and West Virginia. Farther north, the brood is also expected to take shape in smaller pockets, in Cape Cod, Massachusetts; Long Island, New York; and central Pennsylvania.
When will Brood XIV emerge?
The brood will emerge before the end of spring on June 21, but cicadas’ arrivals in different parts of the U.S. will likely vary.
Cicada expert Matthew Kasson told CBS News in 2024 that the exact timing of a brood’s emergence is linked to the temperature of the soil they’re in before moving above ground. Kasson said cicadas are prompted to exit the soil when it reaches 64 degrees, so groups within the larger brood may travel to the surface sooner than others in cooler locations.
What do cicadas do?
The life cycles of periodical cicadas are closely tied to how and where they emerge. Before a brood materializes on land, each of its members — sometimes trillions of them — exist underground as larvae, subsiding on fluids from plant roots, according to the National Wildlife Federation. They live in those conditions for 13 or 17 years, depending on their brood. Then, almost all at once, the insects burrow upward and break through the surface of the soil, often making their presence known by erupting in loud and at times constant choruses.
Conspicuous noises from cicada swarms are a mating tactic, the wildlife federation writes, as the male insects gather in groups and create loud sounds to attract females. The mating process begins within a few days of cicadas emerging. When it ends, the females cut shallow grooves into tree branches and lay their eggs inside. Researchers at Arizona State University say those eggs usually hatch within 8 weeks, and newly born cicadas fall from the branches down to the ground. Called nymphs at that point, the young bugs proceed to dig their way back underneath the soil, where they remain until it’s time to emerge again.
Adult cicadas typically remain above ground in a given location for 4 to 6 weeks after they first emerge. Researchers note that most of the individual insects live for less time, but that window accounts for some degree of staggering when the brood emerges, since that happens over a period of about two weeks.
Are cicadas dangerous?
Cicadas are not dangerous to humans or pets, experts say. They don’t bite or sting and they aren’t poisonous or venomous.
“If dogs or cats eat many cicadas, this may temporarily cause an upset stomach or vomiting, but there is no need to worry if a pet eats a small number of cicadas,” the Environmental Protection Agency says.
They are also largely beneficial to the ecosystem. They are a food source for birds and other predators that eat insects. They can aerate soil, and when they decompose, they provide nutrients that can help trees grow.
Cicadas may harm young trees, which can be protected with mesh or netting. They don’t eat leaves, flowers, fruits or garden produce, the EPA says.
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