The name Cicada (Superfamily: Cicadoidea) represents approximately 2,500 species of insects living on every continent in the world except Antarctica. Though sometimes referred to as locusts, cicadas are unrelated, and are more closely aligned with leafhoppers. Cicadas are recognized the world over for their absence, followed quickly by the appearance of thousands of the insects seemingly overnight. Though some species do appear every summer, there are others that are only visible once every 13 or 17 years, and come by the billions.
Adult cicadas are very large insects, with most measuring 1-2 inches in length and some tropical species reaching 6 inches. They have long, clear wings and noticeable compound eyes that can be a variety of colors, even bright red, depending on the species. Their bodies also exhibit a number of colors and patterns depending on species.
The cicada is largely recognized for its deafening song which can reach over 120 decibels and actually damage human hearing. The song is not caused by vocalization or rubbing appendages together as with crickets. Rather, the cicada has tymbals, membranes of muscle on the side of its abdominal base, which can be contracted and relaxed to make a loud clicking noise. Both sexes have these tymbals, but only males use them to make a mating call. The sound of thousands of male cicadas calling at once is a familiar part of summer for many people around the world.
Depending on species, cicadas live anywhere from 2-17 years. However, the vast majority of their lives are spent as nymphs well out of sight from humans. After mating, a female cicada will cut slits in the bark of a tree branch, laying many hundreds of eggs. After hatching, the nymph cicadas will descend to the ground and burrow anywhere from 1-9 feet into the dirt. Depending on the life cycle of their species, the nymphs will spend the next 2-17 years underground, feeding upon juice from plant and tree roots.
When it is finally time to emerge, the nymphs will come to the surface and crawl to a nearby tree or plant to molt. After a few hours, they crawl out of their old skins (leaving the skins attached to the tree or plant) as adults capable of flight. They will then spend the next few months feeding on tree sap and attempting to locate a mate. The cicadas have approximately 2 months of time above ground before they perish. Because of the various life cycle lengths of different species, some cicadas are usually present every summer. However, the 13 and 17 year cicadas often appear by the billions in years where they emerge.
- 13 and 17 year cicadas can emerge in such great numbers that population densities will exceed 1.5 million individuals per acre.
- Cicadas do not bite or sting, but can pierce human skin with their feeding tubes if they mistake an arm or leg for a tree. This is rare and can be avoided simply by brushing the insect off if one lands on you.
University of Michigan Museum of Zoology