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Loud Bug Summer: All Your Cicada Questions, Answered

By Sebastian Echeverri on 31. May 2024
Sebastian Echeverri

Summer is here, and the cicadas are ready to party (but mostly scream at each other). Depending on where you are, they might just be some daytime background noise, or so numerous that they are impossible to ignore. We have information to help you share the season with these loud bugs! 


A periodical cicada perched on a stem. Its body is black, with orange legs and bright red eyes, and stands out dramatically against the green leaves in the background.
Cicadas come in many varieties. The bold colors of Magicicada are very noticeable, although they are often heard well before you are close enough to see them. (Photo: Katja Schulz CC-BY)


What are cicadas?

Cicadas are a type of insect, like bees, butterflies, and beetles (and indeed, most animals). There are over 3,000 species across the world. They have stocky bodies, short antennae, wide-set eyes, and (as adults) two pairs of often transparent wings. They spend the vast majority of their (often long) lives underground, and only emerge for a few weeks at the end of their lives to mate and lay their eggs.

Cicadas are sometimes called “locusts”, because both of these insects share the behavior of showing up suddenly in large numbers. However, locusts are grasshoppers, which are not closely related to cicadas, and swarm for different reasons.


What is the difference between annual and periodical cicadas?

The vast majority of cicada species are “annual”, meaning that some members of the species emerge every year. However, even annual cicadas will spend multiple years underground.


A common swamp cicada, sitting on the ground by some fallen leaves and barks. The cicada’s green, black, and brown coloration helps it blend in.
Annual cicadas, like this common swamp cicada (Neotibicen tibicen ssp. tibicen), have colors that help them blend in with their surroundings, unlike periodical cicadas. (Photo: Andrew Block CC-BY-NC)


Periodical cicadas are special, because an entire population will emerge all together, then vanish by the end of the summer, only to be seen once more after many years. This repeats every certain number of years. This periodical life cycle is incredibly rare in animals. We currently only know of 9 species of periodical cicadas, and one species of periodical millipede.

Most periodical cicadas are in the genus Magicicada, with 7 species. All live in North America, with four species following a 13-year cycle, and three species on a 17-year cycle. 

What is a cicada brood, and what do their numbers mean?

Within a given region, different species sharing the same life cycle will all emerge together. These groups are called “broods”, each with their own number in Roman numerals (although the numbers themselves are arbitrary and do not mean anything special).

For example, in 2024, a group of 13-year cicadas called Brood XIX (“nineteen”), is emerging across many states. This brood includes all four species of 13-year cicadas, but others may not.


A map of the USA east of the Rocky Mountains, showing the different broods of periodical cicadas, and listing the years that they will emerge. 
Periodical cicadas are spread throughout much of North America east of the Rocky Mountains. Different broods take up different regions, but often overlap at their edges. (Photo: USDA Forest Service CC-BY)


Why do so many cicadas show up all at once?

Periodical cicadas emerge in large groups in order to avoid predators — sort of. Each individual cicada doesn’t have much in terms of defenses or ways to escape being eaten. Predators, such as birds, cicada-hunter wasps, and squirrels, will feast on the seemingly endless supply of food. But at a certain point, there are simply too many cicadas for their predators to eat, and the rest can safely find mates and reproduce. 


Why are there so many cicadas this year?

The summer of 2024 is especially full of periodical cicadas because two different broods are emerging together. Between Brood XIX, a group of 13-year cicadas, and Brood XIII, ironically a group of 17-year cicadas, approximately one trillion cicadas will arrive, across 16 states. This incredible spectacle only happens every 221 years! 


When will the cicadas show up, and when will they be gone?

Cicadas will begin to emerge from underground once the soil is warm enough, about 64 degrees Fahrenheit at six inches deep. They will climb up a tree, and the molt into their adult forms, complete with wings.


A number of Brood X periodical cicadas that have just undergone their final molt. They are still pale yellow and their wings are in various stages of unrolling. The nymphs climbed up this milkweed plant to molt.
After molting, cicadas will be pale, before their exoskeleton slowly darkens and hardens. (Photo: G. Edward Johnson CC-BY)


Adult cicadas only live for a few weeks. Before dying, females will lay their eggs in tree branches. At the end of the summer, the eggs hatch, and the babies will drop down and begin to burrow underground.

While underground, cicadas count how many years have passed by noticing changes in the tree sap they drink that correspond to the seasons. Whether a periodical cicada will wait 13 or 17 years is determined by their genes. 


Why are cicadas so loud?

Whether or not you’ve seen one up close, you likely have experienced cicadas’ most obvious claim to fame: their sheer, un-ignorable, loudness. Cicadas are some of the loudest animals in the world, despite being much smaller than many of their noisy competitors.

Cicadas have a special built-in instrument called a “tymbal”. Tymbals make a clicking sound, but cicadas make this sound over and over so rapidly that we hear it as a constant hum.

Once they become adults, male cicadas spend all day screaming from the tree tops to attract a mate. In some species, males gather together in a chorus, to make even more noise than they could by themselves. Groups of periodical cicadas can be as loud as lawnmowers or leaf blowers. While all this screaming might not be very musical to most humans, each cicada species has its own particular variety of song, which they use to tell each other apart – and we can use to identify them!


What do cicadas eat?

Cicadas get all their food by drinking a watery sap (xylem) from trees. Cicadas don’t have a mouth that opens and closes. Instead, they have a straw-like tube that they insert into the tree. Baby cicadas drink from a tree’s roots, and adults from the branches.

Xylem sap isn’t very nutritious, so cicadas have to drink a lot of it. Like other animals that eat large amounts of low-nutrient food, like mammals that eat only grass or leaves, they have a lot of “useless” parts of their diet. Thankfully, instead of the large amounts of solid dung that grazing mammals make, after cicadas take the sugar from the xylem sap, all that is left is water. The cicadas will regularly pee out this extra water as they feed on a tree. While experiencing “raindrops” underneath a tree on a sunny day might be unexpected, it is not harmful to us (or our clothes).


Are cicadas dangerous to me or my pets?

Cicadas are not dangerous to other animals. They cannot bite or sting. At worst, they can bump into things (including us) while flying, as they are very clumsy. While cicadas can be very loud, especially in groups, they don’t pose a risk of hearing damage unless you deliberately put your ear close to them while they are singing (so don’t do that).

Pets might want to catch and eat the cicadas – this is safe, just don’t let them eat too many in a row as the bugs’ exoskeletons can be tough to digest when uncooked. People can eat cicadas, too (and have been doing so for a very long time). You can find many cicada recipes to experiment with!


How do I keep my plants safe from cicadas? Are cicadas pests?

There’s very little you need to do, as cicadas are actually helpful for most plants. They aerate the soil as they burrow through it, and when they die, their bodies fertilize the soil.

While cicadas do feed on trees, only younger, more delicate trees are at risk of lasting harm. You can easily protect young trees by covering them with a mesh net. Older trees may lose a branch if many cicadas lay eggs in it, but the overall tree will survive and grow another.

Do not use pesticides to control cicadas! You will end up harming your local ecosystem. Pesticides will kill many other animals besides just the cicadas, including pollinators like bees and butterflies.

Let the cicadas have their few weeks of partying; they’ve been waiting patiently for over a decade.

The ground covered in periodical cicada adults and many shed exoskeletons. There are so many cicadas that the ground itself is barely visible. 
Periodical cicadas, and their shed exoskeletons, will cover the ground in many parts of the country. (Photo: James St. John CC-BY)


How can I get the most out of this loud bug summer?

In patience, we wait
To finally sing our song
Please, let it echo on

- Staci Cibotti

In soil they slumber
Years pass, they rise in chorus
Respect their journey

- Emily May

Cicadas are here
Don’t spray - there’s nothing to fear!
Just enjoy their song

- Aaron Anderson



Dr. Sebastian Alejandro Echeverri, PhD (he/him) is your friendly neighborhood spider scientist, wildlife photographer, and science communicator. He joined Xerces in 2024 as a communications specialist for science and digital media, and is excited to continue making bugs (and bug conservation!) more accessible, inclusive, and joyful for everyone.

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