The species of periodical cicada emerged in our area in 2013 (Magicicada septendecim L.) spends 17 years developing underground as a nymph, feeding on sap from tree roots. For a short time in early summer of the 17th year, the nymphs of the entire brood emerge around sunset, climb up tree trunks and transform into beautiful winged adults that have black bodies with red and yellow trim, ruby-like eyes and stiff glossy wings. Within a week males begin to sing a high-pitched song to attract females. After mating, the females then carve tiny slits in small tree branches and lay their eggs. Though sometimes small branches may wilt, the cicadas rarely cause any significant damage to entire trees. The adult 17-year cicada lives for no more than a few weeks. After mating and egg-laying, they quickly die. When the eggs hatch later that same summer, the tiny nymphs climb down and burrow into the ground to begin their long underground development.
For people who live or work in the habitat of the 17-year cicada, its emergence sometimes causes concern. These species emerge in vast numbers because their only defense against predators is “predator satiation” —their sheer numbers overwhelm the appetites of predators. But 17-year cicadas are completely safe. They do not kill trees or other plants, and do not sting, bite or harm humans or other animals. They are even safe for pets (and us!) to eat. To preserve their unique way of life, the Yale Peabody Museum strongly discourages the use of pesticides or other measures that can be harmful to these remarkable creatures.