Larry Caplan, Extension Horticulture Educator, Vanderburgh County, IN
Southern Indiana residents should begin stocking up on ear plugs now…because Brood XXIII of the 13-year (periodical) cicada is due back this month. According to my records, when this brood was last here in 2002, they showed up in great numbers throughout southwest Indiana.
Periodical cicadas are about 1 and 5/8 inches long. They have black bodies, with red eyes, legs, and wing margins. The adults usually appear in the last part of May and throughout June. When they appear, the males make an incessant, shrill, high-pitched mating call. They produce this sound by vibrating membranes on the undersides of their abdomens. The females do not make any noise.
After mating, the female cicada uses a knife-like organ to slit or puncture the twigs of woody plants, into which she lays her eggs. In about six weeks the eggs hatch, and the young nymphs drop to the ground. They’ll burrow into the soil and feed by sucking the sap from the tree’s roots. The nymphs will remain underground for 13 or 17 years (depending on the brood).
When nymphs emerge from the ground, they leave large, dime-sized holes in the soil. They crawl up tree trunks, fences, and other vertical objects where they molt (shed their shells) and turn into winged adults. Adults live for about a month during which time the females can lay between 400 and 600 eggs.
In urban areas, heavy infestations can make sidewalks and roads slick with dead insect carcasses. In orchards, nurseries and landscapes, young trees with stems and branches less than 3/4 of an inch can be seriously damaged by the egg-laying process. Small twigs and branches turn brown, die, and sometimes break off.
Controlling cicadas is pretty much impossible. Young or recently transplanted trees can be protected by covering them with screening or floating row covers. These materials allow sunlight in, but do not allow cicadas to reach the stems for egg laying.
Pesticides are generally not recommended. Cicada adults do not feed on the trees, so they won’t ingest much of the chemical. Permethrin or other synthetic pyrethroids are labeled for cicada control, however, in most cases these chemicals must be reapplied several times during the cicada flight period (six weeks) to be effective - making their use somewhat impractical. Be sure to read and follow all label directions.
If periodical cicadas emerge in your neighborhood, please email LCaplan@purdue.edu, or call (812) 435-5287 so that the monitoring of their emergence can continue.