The female cuts a slit in the tips of branches to lay her eggs,'' Crutchfield says. She may cut four to 20 slits in a single branch. It causes the tips to die.'' Because annual cicada numbers are so evenly distributed each year, they cause minimal damage to trees. Annual cicadas are larger than periodical cicadas, averaging about two inches in length. They tend to have mottled dark-green bodies, green eyes and green legs.
Periodical cicadas are smaller, averaging about an inch and a half in length.
They have black bodies, red eyes and orange legs. The adult of both types of cicadas lives only a few weeks. People have little to fear from cicadas despite their menacing appearance. Despite Americans' familiarity with the sounds of the annual cicada, it remains one of the least understood of all cicadas. Crutchfield says the majority of research focuses on the periodical cicada.