Cicadas, Cicadas Everywhere

Where were you and what were you doing in spring 2004? If you were in Maryland or anywhere in the Eastern United States, chances are you were busy being fascinated by (or perhaps trying to avoid) big, bumbling black bugs with red eyes and clear wings. This spring, these periodical cicadas known as Brood X are emerging for the first time in 17 years and Maryland is right in the middle of the action.

Brood X is one of 15 broods of periodical cicadas native to the Eastern U.S. All periodical cicadas of the same life cycle type (either 17 or 13 years) that emerge in a given year are known collectively as a single brood. Each brood is designated with a Roman numeral, so that's a ten, not the letter x. Brood X, which has the widest range and biggest concentration of any of the periodical cicadas, is expected to appear in Washington, D.C., and 13 states in addition to Maryland: Delaware, Georgia, Illinois, Indiana, Kentucky, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia.

As temperatures rise and the ground warms in May, cicada nymphs will emerge from the soil where they've been developing for the past 17 years. They'll shed their brittle, tan-colored exoskeleton, move to the treetops and get busy attracting mates. Females will lay eggs in tree bark, then it's game over for the grown-ups. Adult cicadas are usually active aboveground for about 8 weeks before they die off in mid to late June. Their offspring will hatch in August, and the immature nymphs will drop from the trees to the ground, where they will burrow into the earth, not to emerge for another 17 years.

The appearance of millions of these large insects at one time can be unsettling, but cicadas are harmless. They do not bite, sting or threaten people in any way. If they fly into you, it's because they've been underground for 17 years and are new to the whole flying-around-in-the-air thing. Humans do, however, threaten cicada populations. Cutting down trees, paving over soil and using pesticides and other chemicals all impact cicadas and other wildlife.

Cicada Smorgasbord

Cicadas are a valuable food source for many species. Birds and mammals will all-out feast on cicadas over the next few weeks, as will turtles, snakes and even fish. Periodical cicadas' survival strategy is known as "predator satiation." There are so many of them all at once that predators can't possibly eat them all. Huge numbers of them can be eaten, and a significant number of individuals still survive.

Copperhead snakes, one of two venomous snake species found in Maryland, do opportunistically feed on cicadas, but suggestions that the cicadas' emergence will lead to an increase in the state's population of copperheads are not true. Copperheads are a beneficial and protected species, and cicadas will not attract more of them.

If the City Nature Challenge sparked your interest in community science and you want to do more, download Cicada Safari to help map the 2021 emergence of Brood X. And hop (fly?) to it: in just a few short weeks, these interesting insects will be gone, not to be seen again until spring 2038.

Fun Cicada Facts

• Cicadas are arthropods; they belong to the same phylum as shrimp, lobsters, crabs and other invertebrate insects, arachnids and crustaceans.
• Locusts and cicadas are not the same. Locusts are large, flying grasshoppers, swarms of which can destroy crops and vegetation. Cicadas feed on sap from tree roots, twigs and branches and generally don't cause harm except to young trees.
• A cicada's straw-like mouth is called a rostrum. Dolphins, sawfish and other aquatic animals have rostrums, too. It is a common name for the beak or snout of many animals and insects.