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.

Cicadas are poised to return at some point in the spring of 2025, potentially bringing billions of bugs to neighborhoods across the eastern United States. 

The group of cicadas set to appear has been labeled Brood XIV. Emerging once every 17 years, Brood XIV is the second-largest group of periodical cicadas — which rise from underground en masse — and will be the only group this spring. That means there will likely be fewer cicadas above ground than there were in 2024, when multiple broods of cicadas emerged at the same time.

Where will cicadas emerge in spring 2025?

Cicadas this year will likely be concentrated in Kentucky and much of Tennessee. The insects from Brood XIV are also expected to show up in parts of Georgia, Illinois, Indiana, North Carolina, Virginia and West Virginia, in addition to smaller pockets farther north in Cape Cod, Massachusetts, central Pennsylvania and Long Island, New York.

CBS News’ data team created an interactive map that shows where cicadas are expected to be this year. The map uses information from the University of Connecticut’s Cicada Project, which plots the brood’s spread based on its known locations in the past. 

When will cicadas emerge in spring 2025?

The huge groups of cicadas emerge when the soil reaches about 64 degrees Fahrenheit, according to University of Connecticut researchers. In warmer states, cicadas usually come out in late April or May. In cooler states, their arrival tends to occur in May or early June.

How long will cicadas be above ground?

Researchers say cicadas typically remain in a given area for 4 to 6 weeks after they first emerge. Most individual cicadas live for just a few weeks, but, since the emergence itself happens over two weeks, their eventual fading will also be staggered.

What are cicadas?

Cicadas are a type of insect, related to stink bugs, bed buds and aphids. The ones expected to arrive in droves this year are a variety called periodical cicadas, which appear in huge swarms and often create loud buzzing sounds, according to the National Wildlife Federation. Annual cicadas exist as well.

Periodical cicadas have earned a reputation across eastern North America because of their conspicuous recurrence. Individual “broods” are biologically synchronized to crop up simultaneously in 13- or 17-year intervals, when they rise from their burrows underground in populations that can reach up to the trillions. Between intervals, they live in soil as larvae and feed on fluids from plant roots, the wildlife federation explains.

There are three species of cicadas that emerge every 17 years, and four species that materialize every 13 years, according to researchers at the University of Connecticut. When cicadas share the same emergence year, they’re considered part of a brood. 

The interactive map below shows where different broods are scattered across the country.

Why do cicadas make noise?

The noise people often hear from cicadas is a mating tactic, according to the wildlife foundation, which notes that male cicadas tend to crowd together and produce raucous choruses in efforts to attract females. Once the mating process has ended, female cicadas deposit their eggs in tree branches. When they hatch, the larvae fall to the ground, burrow into the soil, and the cycle starts again.