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Get out your earplugs. In spring 2024, as the ground warmed, billions — perhaps trillions — of periodical cicadas came up in a rare dual emergence: two separate broods surfacing at once across the Midwest and the southeastern United States. The same pair won't coincide again for 221 years, until 2245.
Image from the National Park Service's page on cicadas
Meet the cicada
Cicadas are true bugs (order Hemiptera). Their young, called nymphs, live underground feeding from tree roots, then climb out and molt into adults. Males sing to attract females, and every species has its own song — a new species was identified by its song as recently as 1998.
Annual vs. periodical
| Annual cicadas | Periodical cicadas | |
|---|---|---|
| When | every year, around July | only after 13 or 17 years underground |
| Where | across the lower 48 states | the Midwest and East |
| Look | larger, usually green or brown | slightly smaller, with red eyes and orange wings |
| Species | over 100 in the U.S. | seven |
Periodical cicadas are sorted into broods that surface in different years and places, when the soil reaches about 64 °F: 12 broods of 17-year cicadas and 3 broods of 13-year cicadas. They live above ground for only a few weeks.
A periodical cicada. Photo by Nortrup, National Park Service
Why 2024 was special
Broods usually come up in different years with little overlap. In 2024, Brood XIII (17-year) and Brood XIX (13-year) emerged together.
Why so many at once?
Surfacing in huge numbers for a short time is most likely an evolutionary strategy against predators. Birds, reptiles and small mammals all eat cicadas, but they can't eat them all; plenty survive to breed. This is called prey satiation.
Photo by the National Park Service
Good neighbors
- Native insects that feed on sugars in tree roots, cicadas don't damage flowers or crops.
- They are a rich food source for many animals.
- Their burrows aerate and cycle the soil.
- They pose no real threat to mature trees, but females laying eggs can damage small branches — so where they emerge, consider covering young trees with mesh or netting.
Are they dangerous?
No. Cicadas don't bite or sting and aren't venomous or poisonous — if your pet eats a few, there's no need to worry. They're just loud.
The life cycle in brief
- Adults sing for mates and lay eggs in branches.
- Tiny nymphs hatch and drop to the ground.
- Nymphs feed on tree sap underground — for up to 17 years.
- Nymphs emerge and molt into adults.
Image from the National Park Service's page on cicadas
Sources
Based on "I Didn't Know That!: Emerging Cicadas," National Park Service; a work of the United States government in the public domain.
Licence : CC0 1.0 (domaine public) · Adapté de www.nps.gov
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