INCREDIBLE INSECTS: A Celebration of Insect Biology

Periodical cicadas only occur in the eastern United States.
Periodical Cicadas are one of the most remarkable phenomena of nature. They suddenly appear in the millions, keeping people awake at night with the deafening racket of their mating calls. Then they disappear as suddenly as they came, not to return until kindergartners have graduated from college and college professor have retired.

Periodical cicadas differ from other cicadas in that they have exceptionally long life cycles. It can take thirteen or seventeen years for one to grow from egg to adult. There are twelve populations (called broods) of periodical cicadas with a seventeen-year life cycle (often erroneously called seventeen-year locusts), and three broods with a thirteen-year life cycle.

All individuals in a given brood come out within a two-week period. The adults lay eggs, the larvae hatch and burrow underground to feed on the roots of trees and will emerge all together, as adults, thirteen or seventeen years later. Each brood occurs in a different part of the country, so that at any given location the cicadas only appear every thirteen or seventeen years.

Brood XIX emerged in our part of Central North Carolina in 2011, and will not be seen again until 2024. This year (2017), brood VI emerges in Western North Carolina.

There are three species of periodical cicadas in every brood. The three species look identical to each other, but have very distinctive mating calls, illustrated by these sonograms, by which they tell each other apart.

Cicadas vary widely in size, and tropical cicadas can be very colorful, as shown by these species from Southeast Asia, sometimes called butterfly cicadas: (left) Tosena fasciata, Tosena splendida, Gaeana cheni, Gaeana festiva, (right) Trengganua sybylla, Angiamina floridula, Ambragaeana ambra, Khuanalna electra.

Cicada larvae feed on the roots of hardwood trees. When fully grown they come out, metamorphose to the winged adult, leaving these larval shells behind.