Wikijunior:Bugs/Cicada

What does it look like?
Cicadas are large insects between 1 and 2-3/8 inches long. Most are black with greenish markings. They have a stout body, a broad head, and short antennae. Their large compound eyes are set wide apart. Three small eyes (ocelli) are arranged in a triangle. Clear wings with sturdy veins are attached to the thorax. Wings are held roof-like over the abdomen. There are six legs with strong claws for gripping bark. Immature cicadas look like adults, but have tiny wings or no wings at all. Males have sound-producing organs below the base of the abdomen. Cicadas are sometimes called locusts but do not jump like locusts.

Periodical cicadas are 3/4 to 1-1/4 inches long. They are black-to-brownish in color with reddish-brown to yellow under the abdomen. Wings have an orange tinge; legs are reddish. Front wings are twice as long as back wings. Wingspan can be up to 3 inches. One Chinese species is 7 inches long with an 8-inch wing span!

Some cicada species are colorful. Magicicadas have black bodies, red eyes, and wings with orange veins. Near the tip of each forewing is a black "W". The species Okanagana is colored black and orange. “Stop-and-go" cicadas of Ecuador have wings with red and green markings. Some cicada species are odd looking. The male bladder cicada of Australia has a large, balloon-like abdomen.

Scientists identify cicada species by their sounds or “songs”. Male cicadas have 2 thin membranes (tymbals) on the sides of the abdomen. Muscles pull the tymbals inward to make a clicking sound. When muscles relax, the tymbals snap back to make a different sound. This happens 300 times per second! The hollow abdomen amplifies the sound like a drum.

Where does it live?
Periodical cicada species (Magicicada) are found east of the Mississippi River from the Great Lakes to the Gulf of Mexico. Their habitat is deciduous mixed forests and nearby grasslands and pastures.

Unlike other cicadas, periodical cicadas emerge only once every 13 or 17 years. When they all emerge at one time they are called a “brood”. Some broods are large while others are small. There are only 14 broods of 17-year cicadas and 5 broods of 13-year cicadas in the United States. The 17-year species are mostly in northern regions. The 13-year species are generally in southern and midwestern regions.

What does it eat?
Cicadas belong to the insect order Homoptera because they have sucking mouthparts. Insects in this order pierce a root or stem then suck up the fluid from plants. Periodical cicadas feed on the sap of tree roots to get food. This is how they stay cool in the summer and keep from drying out.

How does it defend itself?
Insect-eating birds and various animals eat cicadas. Male cicadas use vibrating membranes on the abdomen to warn of danger. Cicadas can fly away from predators. They are fast fliers, but sometimes bump into trees and other objects. Enemies are usually overwhelmed by the sheer number of emerging cicadas. Predators eat their fill and many cicadas remain.

What stages of metamorphosis does it go through?
Cicadas undergo simple or incomplete metamorphosis. There are three stages of development— egg, nymph, and adult. To lay eggs, females use an ovipositor to make a slit in a twig. The twig dies and falls to the ground where eggs are left. Sometimes young cicada nymphs hatch from eggs and drop to the ground without the twig. Upon reaching the ground, they use strong front legs to dig underground burrows in the soil where they will live.

Cicadas molt through several nymph stages before emerging as adults. There are no larva or pupa stages. When the soil gets warm enough in spring (about 64 degrees F), nymphs dig exit tunnels to find air. They climb a tree to undergo one last molt. When the exoskeleton splits down the back, the adult wriggles out.

Newly emerged adults are milky white. In 2 or 3 hours their bodies turn black. The wings are thick little flaps. Fluid pumps through a network of veins to expand the wings. The wing veins turn bright orange and eyes turn bright red. When wings unfold and dry out, cicadas crawl or fly up to the treetops.

Most cicada species have lifecycles between 2 and 8 years. These species are often called "annual" cicadas. Annual broods overlap so adults can be found every year. Species in each lifecycle group have different sizes, colors, and songs. In contrast, “periodical” cicadas mature together in long lifecycles of 13 or 17 years. Periodical cicadas have a 3-stage lifecycle too, but spend many years as nymphs. Most of the emerging periodical cicada broods contain 2 or 3 species. Annual species appear every year in midsummer. Thousands of empty nymph skins can be seen hanging from trees during July and August. They are called “dog day” cicadas. Ancient people believed the sun’s heat combined with heat from Sirius the Dog Star. They called the hot days of mid-summer “dog days”.

The lifecycle of periodical cicadas is between 13 and 17 years. They appear in May and June. Periodical cicada adults are present in a given area only in certain years. Most of their time is spent underground in the nymph stage.

What special behavior does it exhibit?
The word cicada means “buzzer” in Latin. Each cicada species has a distinctive song, such as a loud buzz or hum. Every song varies in tone and rhythm. Some species are more “musical” than others. Sometimes they make a clicking or whining sound. When thousands sing at the same time they are very loud. Male cicadas make sounds using tymbals--special structures found on the abdomen. Male cicadas make sounds to lure females. Males begin making their sounds a few days after emerging from underground. They often stay close together in “chorusing centers” that attract females. They stop singing in the evening.

Periodical cicada nymphs are able to burrow as deep as 8 feet to find roots where they can feed. They are able to tell when thirteen or seventeen years have passed by tasting juices sucked from the roots. These fluids change as trees grow through the seasons. If the cicadas count wrong they will not emerge at the right time.

When they hatch, millions of cicadas suddenly appear as if by magic from soil. They have the scientific name Magicicada. The different broods of Magicicada in the United States usually emerge as adults on separate schedules. Every 221 years they come out together!

How does this bug affect people?
Cicadas have fascinated people since ancient times. They are well liked by people in most countries of the world. In France they are thought to bring good luck. They are a source of food for people in Africa, Asia, and Latin America. In ancient China they were a symbol of rebirth.

In 1634, Pilgrims in New England heard a population of cicadas known as Brood XIV. This population lives in parts of 13 states including Massachusetts where Pilgrims first settled. The Pilgrims thought cicadas were plague locusts like those in Bible stories. Brood XIV last appeared in 2008. The next generation will appear in 2025.

Cicadas cannot bite or sting. They have no economic value. Sometimes, when large populations crowd into a small area, damage can occur. Too many cicadas feeding and laying eggs can harm young trees. Older trees usually escape with little damage.

Reference
Leahy, C. (1987). Peterson’s first guide to insects of North America. Boston, MA: Houghton Mifflin Company.

Milne, L. & Milne, M. (2009). National Audubon Society Field Guide to North American Insects and Spiders. New York, NY: Alfred A Knopf.

Pringle, L. (2010). ''Cicadas! Strange and Wonderful.'' Honesdale, PA: Boyd Mills Press.

http://animals.nationalgeographic.com/animals/bugs/cicada/

http://bugguide.net/node/view/111296

http://insects.ummz.lsa.umich.edu/fauna/Michigan_Cicadas/Periodical/Index.html