Where are the cicadas now?
The fully grown periodical cicada nymphs are currently in small underground chambers about 8-12 inches below the soil surface beneath their host trees, where they have been feeding on root sap since 2004. Host trees can be found in forests, parks, and even urban and suburban neighborhoods — wherever there are mature trees that were present during the last emergence.
When will they start emerging?
In our area, the nymphs typically start to emerge in early May, but only when soil temperature reaches approximately 18 degrees Celsius (64 degrees Fahrenheit). The nymphs mostly emerge from their underground tunnels at night, enabling them to complete their final molt into adult cicadas under the protective cover of darkness.
How do they tell time?
We know part, but not all, of the answer to that question. Because developing cicada nymphs are tapped into the roots of trees, they can sense differences in the sap in the roots throughout the year, and can count the seasonal pulses of sap. They emerge after 17 cycles have passed. We don’t yet know how they keep track of how many years have passed, however.
What do cicadas eat?
Cicadas are herbivores, which means that they eat plants. Their mouthparts (rostrum) are shaped like straws which they insert into plants to sip sap. Cicadas nymphs sip sap from tree roots for the 17 years that they live underground. Once the adults emerge they feed very little, but they might take a drink here and there, which doesn’t harm the plants. Because the plant fluids that they feed on are mostly water and not very nutritious, cicadas depend on special bacteria that live inside their bodies to provide other nutrients and amino acids that they need to grow.
Why are there so many?
The synchronous emergence of millions of adults all within a few weeks clearly works to ‘satiate’ all available predators, ensuring that many will survive to reproduce the next generation. When mistakes are made and a small portion of a brood emerges 4 years early (a common occurrence for 17-year cicadas which we observed for Brood X in 2017), they typically don’t survive or reproduce well.
Why do they come up every 17 years?
That is still a bit of a mystery. Seventeen years is a very long life span for any insect. In fact, periodical cicadas are among the longest living insects on record. There are species of both 13- and 17-year cicadas in the eastern U.S. One line of thinking suggests that having long intervals between successive emergences helps to prevent potential predators from ‘tracking’ these cycles.
Do they ever get their triggers/signals mixed up and emerge early or late?
Yes! Broods of 17-year cicadas often contain a subset of individuals that predictably emerges 4 years early, a phenomenon that is not well understood. This early emergence is one way that the 13-year cicada species are thought to have evolved. Also, there are often a smaller number of individuals that emerge 1 year early, which happened locally in the spring of 2020. Early emerging cicadas are called ‘stragglers’, even though they come out early. The eyes of periodical cicadas change from white to red the year prior to their emergence.
Why do they make so much noise?
Male cicadas sing by vibrating special organs on their abdomens called tymbals. The songs are produced to attract females as mates. The females will make clicking noises back if they like a males singing. Cicadas often congregate in the canopies of individual trees in what is known as ‘chorus’ which can be quite loud! The songs of male cicadas are among the loudest noises made by any insect.
Can cicadas hurt people?
Individual cicadas are quite harmless. They don’t have stingers or biting jaws. They are very awkward flyers so they may accidentally bump into you, but they can’t bite you. If you pick them up, little spikes on their legs might tickle your hand. En masse, cicadas can present a risk to pedestrians and drivers. When many cicadas die on sidewalks, they can make the surface slippery. Walk and drive carefully when navigating large swarms.
Where do cicadas lay eggs, and when will the eggs hatch?
After mating, female cicadas will fly off in search of trees in sunny locations, often along the edges of woodlots or in suburban areas. They then look for small twigs on the ends of branches that are about the diameter of a pencil, where they cut open a slit in the bark using their ovipositor. Inside of this slit, they lay about 20 eggs (called an ‘egg nest’) and each female will fashion many different egg nests (typically laying a total of several hundred eggs). The eggs take approximately 6-8 weeks to develop, typically hatching in mid- to late-summer in our area.
WIll they damage my plants?
Adult cicadas rarely feed above ground on plants. However, female cicadas can damage the small branches of trees when they lay eggs. They prefer to lay eggs on trees that get a lot of sunlight, so trees near the edges of forests or in open areas of yards can be prime targets. They are unlikely to kill your trees, but they might cause some damage. For homeowners, pesticides are ineffective, dangerous, and bad for the environment. A safer and more effective solution is to cover any young trees and shrubs in plastic netting that can then be removed following the emergence.
Who eats cicadas?
Most birds and mammals, and even many insects will eat cicadas. Many different species of birds, squirrels, chipmunks, mice, racoons, opossums, foxes, and even fish will feed on them. Dogs and cats will eat them readily. Eating a few won’t hurt your pets, but If they eat too many it can make them constipated.
Can humans eat them?
Yes! Cicadas are edible and have been historically eaten by settlers and native people alike. If you want to eat cicadas, we recommend collecting them at night just as the new adults emerge from their shells. They are much less pleasant to eat after they have hardened up. Cook them before eating them. They can be tasty dried in the oven and covered in chocolate or included in a stirfry.
How long do they live as adults?
The adults live a very short time — those that survive predation may survive for 3-4 weeks on average, just long enough to mate and reproduce.
Can I keep cicadas as pets?
It’s best not to capture cicadas or keep them as pets. They have been waiting for 17 years to reach this stage of their lives, and they should be allowed to fulfill their mission of reproducing the next generation that will make an appearance in 2038. Instead of keeping them in a jar, why not find a spot with lots of cicadas outside where you can watch them in nature? You will get a much better understanding of how they act that way. It is okay to collect the shed exoskeletons, though!
Where did periodical cicadas come from?
Periodical cicadas evolved in North America, and are native to the eastern United States
How can I get involved?
Do you want to learn how to identify the different cicadas you see (3 different species will emerge this spring)? Do you want to help scientists learn more about where the cicadas are? You can download Cicada Safari for iOS or Android to learn more about cicadas, identify them, and help with scientific research.