KNOXVILLE, Tenn. – In the next few weeks, the brood of periodical cicadas that last emerged in 2008 will be singing and looking for mates before laying their eggs for the next emergence in 17 years.
The 17-year periodical cicadas of Brood XIV will begin to emerge when the soil temperature at 8 inches deep reaches 64 degrees, which is estimated to be in late April to early May.
Brood XIX of the 13-year periodic cicadas had a spectacular emergence in 2024 in middle and southeastern Tennessee. However, Brood XIV is expected to have a statewide coverage. Based on the University of Tennessee Extension publication SP 341 “Periodical Cicadas,” Brood XIV will be concentrated in most East Tennessee counties and in various counties spread throughout Middle and West Tennessee. “If you are a cicada enthusiast, and missed the Brood XIX emergence in 2024, this year might be another chance to witness a spectacular periodical cicada emergence. If you are not a fan of the insects, don’t worry. They will be gone about a month and a half after their emergence,” says Midhula Gireesh, a UT Extension entomologist.
Periodical cicadas Magicicada have the longest developmental period among insects. Depending on the race or type, they spend 13 or 17 years underground in larval form, feeding on plant roots. The 13-year periodical cicadas are more common in the Southeastern United States, whereas the 17-year cicadas are usually found in northern states. Fifteen broods, designated by Roman numerals, have been identified by scientists. There are 12 broods of 17-year cicadas (I-X, XIII and XIV).
Adults are about 1 inch to 1.5 inches long and mostly black with reddish-orange eyes, legs and wing veins. They are harmless to humans and pets, as they don’t sting or bite. They also do not feed on foliage after they emerge, but their egg-laying process may damage young trees, shrubs and ornamentals. Gireesh recommends protecting young and valuable plants with cheesecloth or tobacco canvas while cicadas are present. Insecticide sprays are not effective.
The periodical cicadas emerging this year were laid as eggs in 2008. When adults emerge, the males quickly try to find mates by singing. That’s the intense loud sound you hear for a few weeks in May and are not to be confused with common annual cicadas that are active during the hot summer months of July through September. Annual cicadas are about 1.5 to 2.5 inches long and have a green and brown pattern or green and black pattern with a primarily white or greyish underside.
After mating, the females start to lay eggs by making slits in twigs of woody plants using her knife-like ovipositor. In each slit, the female lays around 24 to 28 eggs. A single female can lay between 400 to 600 eggs. Eggs hatch in six to seven weeks, and the nymphs, which are white and ant-like in appearance, drop to the ground and bury in the soil to find suitable roots. Nymphs grow slowly and feed by sucking sap from roots, but they appear to have no noticeable effect on the trees. After 13 or 17 years, the nymphs emerge and find places to molt, and the new adults emerge several hours later and take flight.
Adult periodical cicadas live only for three to four weeks above ground. The young of Brood XIV will emerge in 2042.
For more information about cicadas, read UT Extension publication SP 341 “Periodical Cicadas.”
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