Male cicadas attract females with sounds produced by a specialized organ in the abdomen called a tymbal, like a tiny vibrating drum. Every species of cicada has a slightly different song, according to the authors of a 2022 paper in the Annual Review of Entomology. Some are a persistent buzz, some more like a chirp. They are surprisingly loud.
Rival males will try to "jam the signals" with their own competing sounds. Females, who do not sing, show their interest with "sharp wing flicks timed to cues in the male song," the authors wrote.
Periodical cicadas are rare: of roughly 3,000 species worldwide, only seven emerge on predictable but prolonged schedules. Those seven, all belonging to the species Magicicada, exist only in the United States, east of the Great Plains. Some emerge every 13 years and others every 17 years.
Scientists aren’t clear on how the insects know when to come out; some occasionally get their timing mixed up and emerge early or late. The United States also has more than 100 species of annual cicadas, which is why in the heart of cicada country — the Midwest — there’s not often a summer without cicadas buzzing in the trees.
Though periodical cicadas in particular are a bit alarming looking, especially in great numbers — with their red eyes, black bodies and red-orange wing veins — they are harmless. They don’t bite or sting; they don’t damage crops or garden plants.
On the contrary, they are beneficial to the ecosystem, providing food for birds, reptiles, amphibians and small mammals. Burrowing nymphs help aerate the soil and when they die after their short four-to six-week adult lives, their bodies help fertilize it. Egg-laying can damage the branches of saplings, but gardeners can wrap the young branches in cheesecloth to keep the insects away. (Experts advise against plastic mesh, which can snare birds’ delicate feet.)
Cicadas aren't strong flyers and depend on predators not being able to eat enough to meaningfully dent their numbers. Credit: NYSIPM Program, Cornell University/Matt Frye
Cicadas aren’t strong flyers and sometimes make no effort to escape from animals looking for a meal. (The scientific name for their lack of a flight response is "predator foolhardy behavior.") Their survival as a species therefore depends on their emergence in numbers so great that predators can’t possibly eat enough to make a meaningful dent in their numbers.
But human activities pose another threat against which the cicadas have no evolutionary defense. According to a 2019 study published in the journal Biological Conservation, 40% of insect species are threatened with extinction, mainly from habitat loss, pesticide use and climate change.
Insects "have been around for hundreds of millions of years," Martins said. "They're incredibly robust, but they are also incredibly fragile... [and] easily disturbed by the changes that are happening in the environment." Drought and disease have killed and weakened the deciduous trees that cicadas feed on; nymphs may not survive the erratic freezing and thawing of the soil that is occurring more often now, and may be drowned when the soil becomes heavily saturated in increasingly intense rainstorms.
Martins said other broods have gone extinct, and it’s entirely possible periodical cicadas on Long Island could also disappear.
Cicadas still emerge in great numbers where there is intact forest in less developed parts of the country. Filippi said it’s unlikely that cicadas will go extinct entirely.
For those who have the chance to witness a mass emergence, Martins said, "it’s absolutely magical."
Experts urge people who do spot a cicada to take a photo, note the location, and report it. Community scientists can log their find in the entomologist-run app Cicada Safari, or email Lisa Filippi at Hofstra: Lisa.Z.Filippi@hofstra.edu
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