Cicadas

adult cicada
Photo: Jon Yuschock, Bugwood.org

There are two cicadas common in the eastern United States: the dog day (annual cicadas) which occur every summer and the periodical (also known as the 17-year locusts) cicada. Dog day cicadas are up to 2 inches long and are blackish with green markings. Their life cycle lasts 2-5 years, with some adults appearing every year. Periodical cicadas are 1-1 1/2 inches long, with reddish eyes, legs and wing veins. Their life cycle is 13 years in the South and 17 years in the North. All cicadas hold their wings "roof-like" over the body.

Damage to trees from cicadas results from the egg laying habits of the females. The female lays eggs in slits in the bark of twigs. The terminal portions of these twigs may die as a result. When the eggs hatch the nymphs (young cicadas) drop to the ground, enter the soil and feed on roots of plants. The nymphs remain in the soil for years until they mature. Before molting into an adult it emerges from the soil and climbs onto an object, such as the trunk of a tree, shrub, etc. The cast skins may often be seen in the garden. The adults then repeat the cycle. Adults of some species live 5 to 6 weeks.

When large numbers of nymphs emerge from the soil, exit holes may be noticeable in the lawn. Several weeks before emergence, some nymphs construct mud chimneys over the emergence hole. These mounds may be 2-3 inches high and 1-2 inches wide with a hole approximately 1/2 inch wide in the center. The activity may be unsightly but does not permanently harm the turf.