for National Geographic News
The emergence of the Brood X cicadas has gardeners in more than a dozen U.S. states wringing their hands, and worrying about what to do.
Nursery attendants, entomologists, and horticulturists seem united in their advice: Unless you own a nursery or a fruit orchard, there's nothing to worry about.
"What we're telling people is, honestly, there is no big cicada scare. It's not going to do a lot of damage," said Beth Abbundi, a spokesperson for Behnke Nursery in Beltsville, Maryland. "Cicadas won't hurt your garden at all; they don't feed on vegetables and flowers. It's the egg-laying that causes the damage, and only to very young trees. On older, healthy trees, they won't cause any damage."
Mitch Baker, a horticulturist and vice president of American Plant Food, a Washington, D.C.-area nursery, concurs, albeit a bit more cautiously.
"We're in something of an epicenter, and millions and millions [of cicadas] will be emerging here," he said. "The cicadas are not a threat, but you will see evident and obvious damage to younger trees as well as older ones. It can be somewhat disfiguring, but it doesn't threaten the overall health of the trees."
"What we're trying to tell people is that this should be viewed as a natural phenomenon, not something we should fear or get all excited about. It's nature's way of pruning."
The cicadas should begin emerging in early to mid-May after spending 17 years underground as nymphs sucking on tree roots. Once they reach the surface, they quickly morph into winged creatures and spend the entire four weeks of their above-ground lives flying from tree to tree in search of a mate, mating, and then dying.
A female cicada's dream home for laying her eggs is the new growth on a branch of a hardwood or fruit tree.
"The female uses her ovipositor to dig a channel in a branch, where she leaves her eggs—that's what causes the damage," said Mike Schauff, a research entomologist with the U.S. Department of Agriculture's Agricultural Research Service.
A female bent on egg-laying could make anywhere from 5 to 20 slits in a branch before moving on to another one. Twigs or branches the diameter of a pencil or thinner are most often damaged. Around late June, the tips of tree branches will start to droop or flag.
Apple, pear, dogwood, oak, and hickory are favorite hosts, according to the Agriculture Extension Service of the University of Tennessee, but many others have been reported.
"They're not really that interested in pines or any of the evergreens, azaleas, hollies, laurels, and other ornamentals," Schauff said.
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