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They’re Coming! Cicadas Invade!

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This post was written by Science Reference Specialist Ashley Cuffia.

Ever wonder what that sound is during the late spring and summer? Well if you live on the east coast of the United States, be prepared for a loud summer as the 17-year brood of cicadas are coming!

Cicadas. 2004. USDA Agricultural Research Service. U.S. Department of Agriculture.
Cicadas. 2004. USDA Agricultural Research Service. U.S. Department of Agriculture.

This summer hundreds of billions of large, winged, red-eyed, noisy insects will emerge from the ground and blanket large portions of the eastern United States in a buggy mess. This group of periodical cicadas called Brood X, emerges every 17 years and is one of the largest and most broadly distributed groups of periodic cicadas. These differ from annual cicadas that we get every year in late summer to early fall that are usually light green or brown.

Periodic cicadas are part of the genus Magicicada and they will range from northern Georgia to New York, then west to the Mississippi River and the Midwest. There can be as many as 1.5 million cicadas per acre, and even though they look very creepy, they do not bite and will not harm you or your pets.

Life Cycle

The cicada actually has the longest life cycle of any insect. Brood X cicadas have lived underground in a wingless nymph form since 2004 when the last Brood X emerged and laid their eggs. All this time they have been living about a foot or two underground, feeding on the sap of tree roots and growing. When ground temperature reaches 64 degrees Fahrenheit at a soil depth of 8 inches, the nymphs will emerge and metamorphose into winged adults. The dried husks you will find all over the place this summer are the remnants of the metamorphosis process.

Newly metamorphosed adult cicadas are white in color, very fragile and in danger for hours or even a days after they emerge until their new exoskeletons harden. Once matured, they spend 2 to 4 weeks flying around making tons of noise, mating, and being eaten by everything.

The adults will then lay their eggs in trees, which will hatch 4 to 6 weeks later. These larva will then make their way to the ground, burrow down, and wait their 17 years underground to emerge in 2038.

Cicada nymph. 2004. USDA Agricultural Research Service. U.S. Department of Agriculture.
Cicada nymph. 2004. USDA Agricultural Research Service. U.S. Department of Agriculture.

Learn More About Cicadas!

  • Brood X cicadas average 1 to 2 inches long and have a wing span of 3-4 inches. They have black bodies, long wings laced with orange veins, red legs and bright red eyes.
  • The males of the species make the loud noise that you hear, which is their mating call to attract females. Their mating call ranges between 90 to 100 decibels which is equivalent to the sound of a lawn mower. Click on the link to hear what they will sound like: National Park Service audio recording- Grand Canyon National Park Cicadas
  • Almost all periodical cicadas grow and mature into adults at the same time, which is why we witness such large groups every 13 or 17 years. With numbers in the billions, the cicadas have an advantage over the predators trying to feast on them, known as predator satiation. The cicadas will emerge in such a small time frame and in such great numbers that even though a large percentage will get eaten by predators, enough will survive to produce the next generation.

Web Resources

Cultural Entomology Articles

  • Egan, Rory B. Cicadas in Ancient Greece. Cultural Entomology Digest. November 1994. Egan discusses cicada references in Greek literature and mythology.
  • Riegel, Garland. Cicada in Chinese folklore. Cultural Entomology Digest. November 1994. A discussion of the use of the cicada in Chinese medicine and the symbolism in Chinese art and artifacts.


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