A whole generation of cicadas is rising above the soils of the eastern United States this spring after hatching 17 years ago. There will be billions arising from the soil of 25 eastern states in the United States, singing their noisy courtship serenades.
These cicadas are sometimes called the “17 Year Locust” probably because they appear in huge numbers like swarming locusts. But they are not related to either locusts or grasshoppers. They are the cicadas, an insect that actually looks more like a giant fly than like a grasshopper.
Like grasshoppers, all cicadas hatch from eggs, looking like a smaller version of the adult insect. Growth occurs in three stages: egg, nymph, and adult. Cicada eggs are laid in tree branches and trunks. The eggs hatch then the newly-hatched nymphs fall into the ground, where they suck the sap from tree roots. As the insect grows, it sheds its skin several times. After it reaches adulthood, it mates and dies. Juvenile or young cicadas sip sap from tree roots but adults live their few days on fat stored up from its nymph stage for the rest of its life: until it mates, the female lays her eggs, and the adults die.
It is the male that is the noisy one; he sings to attract the female.
Cicadas emerge during the summer. Most of the world’s species (including some in the United States) are called “dog day” cicadas since they emerge in the “dog days of summer” in July and August. The life cycle of these insects is one or two years—and they are not the species that are preparing to swarm in the eastern United States.
Cicadas have a world-wide range, living in every continent except for Antarctica. But the ones that emerge every 13 or 17 years, the Magicada or periodic cicadas live only in the United States from Massachusetts and Wisconsin in the north to Georgia and Louisiana in the south, and from the Atlantic west to Kansas and Texas in the west.
The Magicada or periodic cicadas have the longest life cycle in the insect world—between 13 and 17 years. Cicadas in a given area grow up at the same time and emerge from the ground as adults in groups called “broods.” Temperature (ground temperature of 64°F and above) and time (13 or 17 years as a nymph) seem to be the triggers alerting them to crawl back out of the ground, spread their wings and assert their adulthood. Some broods are bigger than others.
Broods are species and location dependent. There are 15 broods and 15 species. For instance, this year will see the emergence of Brood II , which also appeared in 1996, 1979, 1962, 1945, and before, on a 17 year cycle in Connecticut, New York, New Jersey, Pennsylvania, Maryland, Virginia, and North Carolina. Brood XIX (a 13-year species) appeared in 2011, 1998, 1985, 1972, and before. on a 13 year cycle in Georgia, South Carolina, North Carolina, Virginia, Tennessee, Kentucky, Alabama, Mississippi, Louisiana, Arkansas, Oklahoma, Missouri, Illinois, and Indiana. Next year, 2014, will see swarms by two different species in different locations: Brood III, a 17-year species, will swarm in Iowa, Illinois, and Missouri; Brood XXII, a 13-year species will swarm in Louisiana and Mississippi.
The adults of Brood II (this year’s swarming species) have emerged in North and South Carolina and are emerging as a person travels north toward New York and New England where they should begin to emerge next month. The noisy climax will occur in the early summer with the “singing” (sounding like a buzz saw), swarming, mating, egg-laying, and dying of the cicadas of Brood II completing their life cycle and starting a new one.
Do not worry: cicadas are harmless to humans and pets. You might get poked with its proboscis if one lands upon you and thinks you are a tree. Though they eat tree sap, the damage they cause is by many thousands of them roosting on a single tree during a swarm. They are loud, annoying, and some say delicious. In any case, by late July or early August, they will be “history”—until the next brood comes.