Everything You Need To Know About Cicadas!

Periodical cicadas have black bodies, orange legs and wings, and red eyes. What is really amazing about these cicadas is their synchronized mass emergences and their incredibly long lifespans—13 years in the southern and 17 years in the northern parts of their range. They spend most of that time underground as nymphs and only live for about a month above ground as a winged adult. In Illinois they begin emerging with great numbers in May, peak in early June, and wind down by the end of the month. You can hear them calling throughout the daytime while they are out and about.

Populations of periodical cicadas that emerge together on the same 13 or 17 year intervals are defined as distinct broods. This year is exceptionally special for Illinois because we have the emergence of two different broods of periodical cicadas across the state of Illinois. Brood XIII, the Northern Illinois Brood, consists of 17-year periodical cicadas and covers much of the northern half of Illinois and extends into bordering states. Brood XIX, the Great Southern Brood, consists of 13-year periodical cicadas and covers much of the southern half of Illinois and extends as far south as Louisiana and as far east as the Carolinas! While the two adjacent broods likely do not overlap with each other they do come quite close in a few areas, most significantly in Sangamon county near Springfield, IL. The number of emerging periodical cicadas across the entire range of both broods is expected to be in the trillions. The last time Broods XIII and XIX emerged in the same year was 221 years ago in 1803!

Cicadas that emerge asynchronously are known as annual cicadas because they can be seen and heard every year. Perhaps the most familiar species belong to a group called the dog-day cicadas which are green and brown. They begin emerging in July during the dog-days of summer and remain active through September, sometimes into October in Illinois. Dog-day cicadas also spend most of their life underground, approximately 4-7 years, and live above ground for about 2-3 months. While different species of dog-day cicadas prefer to call at different times of the day you can hear them calling primarily in the evening.

Cicadas spend the majority of their life underground poking their piercing-sucking mouthparts into plant roots to sip on watery xylem sap (plant juices!). When the time comes nymphs will crawl out of the ground and search for something to climb up. Once they find a good spot they hold on tight and shed their exoskeletons revealing their winged adult forms. After a few days, male cicadas will start calling to attract a mate. After mating, female cicadas will then lay their eggs in twigs. After several weeks, tiny cicada nymphs hatch out of the eggs and fall to the ground then burrow into the soil, starting the cycle all over again.

Cicadas, like most insects, have bodies divided into three parts: head, thorax, and abdomen.

On their heads they have: a pair of antennae that help them smell, taste, and sense vibrations; a pair of compound eyes that help them see; three simple eyes called ocelli that detect light and dark; mouthparts bundled together to form a rostrum (aka proboscis) which they can use to pierce into wood (but don’t worry they don’t bite!) and drink through like a straw; and a big bulging region called the clypeus which holds strong muscles used for sucking.

The thorax can be thought of as the locomotion center of the body. Attached to the thorax are two pairs of wings used to fly and six legs used to walk, climb, and hold on tight. The thorax is filled with muscles to flap their wings and move their legs.

The abdomen is the largest body part of a cicada. A stiff membrane full of ridges called a tymbal can be found on both sides of a male cicada’s abdomen. The tymbals are surrounded by muscles which stretch and vibrate the tymbals, and is how cicadas make the sounds of their calls! The part of the abdomen behind the tymbals are filled with air and amplify the sound to become much louder.

On the underside of the abdomen of a female cicadas there is an ovipositor. Cicadas use this to cut into twigs and lay their eggs.

Between Broods XIII and XIX, periodical cicadas are emerging across the eastern US. Scientists studying them and mapping out the boundaries of where they are emerging unfortunately cannot be in all places at one time. Luckily, community science is increasingly becoming a useful tool for scientific research and anyone can participate to help by submitting photos of periodical cicadas they observe to either iNaturalist.org (Website or App) or Cicada Safari (App). Every observation helps!

Go to the University of Connecticut for a breakdown of some of the most up to date science on periodical cicadas.

Did you know that there are multiple species of 13-year and 17-year periodical cicadas? You may be able to tell some of them apart by what their calling sounds like. If you are curious go Cicada Mania to hear them! You’ll also be able to listen to calls of other species including the different species of dog-day cicadas and get regular updates on cicada news throughout the season.

Curious about what the experience of a periodical cicada emergence looks and sounds like? Check out our episode of Curious by Nature on the Brood X emergence 2021. Be sure to check out Part 2 to watch the transformation of a periodical cicada from nymph to adult unfold.