Cicadas are large insects (Order: Hemiptera) that occur worldwide and are commonly recognized for their unique sound. While often referred to as "locusts" in the United States, they bear no relation to true locusts, which are grasshoppers. Cicadas are closely related to leafhoppers and spittlebugs. Cicadas can be found all over the world as symbols, representing transformation, reincarnation and immortality.
Periodical cicadas, Magicicada spp., are the best known and longest lived species of insect in North America. These insects are approximately 1.5 inches long, and they have clear wings with orange veins that are held rooflike over their bodies. Periodical cicadas occur only in North America. They are characterized by having regional broods that emerge in mass every 13 or 17 years. "Dog-day," or annual cicadas, are larger than periodical cicadas and have green to brown bodies with black markings and a whitish bloom. These cicadas emerge in midsummer every year. Cicadas have prominent eyes set wide apart on the head with short, hairlike antennae. The periodical cicada has distinct reddish-orange eyes.
|Annual cicada adult.||Cicada nymph.|
Adult cicadas live only for two to four weeks. During this short time, they feed relatively little by sucking fluid from tender, young twigs. Male cicadas sing to attract females by vibrating membranes on the underside of the first abdominal segment. Female cicadas are silent.
Approximately 10 days after molting, female cicadas will mate and begin laying eggs in tree branches ¼- to ½-inch in diameter. She uses her long, sharp ovipositor to make slits in small tree branches, creating pockets in the branch. Each pocket may contain 20–28 eggs. Eggs are elongate and pearly white in color. The female continues laying eggs in rows along the branch. She may lay from 400 to 600 eggs in her lifetime at various sites. Six to 10 weeks later, the white antlike nymphs emerge and drop off the tree branch onto the ground below. They typically burrow 6–18 inches into the soil and begin feeding on plant roots. During the spring of an emergence year, periodical cicada nymphs may build mud tubes that project 3–5 inches above the soil, apparently to escape wet or saturated soils.
|Periodical cicada adult, feeding.||Periodical cicada adult, emerging.|
Cicadas live most of their lives underground in the nymphal stage. They typically reside in the soil at depths ranging from 1–8 feet, where they use their sucking mouthparts to feed on the sap from tree roots. Cicadas undergo approximately three to five nymphal instars. Periodical cicadas emerge in specific locations once every 17 years in the northern part of their range (including Ohio), and once every 13 years in the southern part, with some overlap in distribution (Figure 1). The "dog-day," or annual cicadas, appear during the long summer days of July and August. These cicadas have two- to five-year life cycles, but adults appear every summer.
|Figure 1. Periodical cicada brood map.|
Adult emergence typically occurs at night. Mature cicada nymphs crawl out of the soil, leaving behind a ½-inch hole. They crawl up nearby trees, vegetation or other vertical objects to molt. Their shed outer skins, or exoskeletons, may be found attached to tree trunks and twigs.
Periodical cicada emergence is often tightly synchronized, with most nymphs appearing within a few nights. Different groups called "broods" emerge somewhere in the eastern United States almost every spring. Ohio has four broods that emerge at different years (Figure 1). Massive brood emergence, usually in May and early June, is believed to overwhelm predators, typically birds. This ensures that enough survivors will be left behind to reproduce. Male cicadas are capable of making a loud buzzing noise, and they squawk when disturbed. The males often synchronize their buzzing in trees. Within each brood there are four or more species. Each species has a different call. It is believed that such droning and squawking is effective in deterring predators.
Annual cicadas usually emerge from June through August. Their emergence is scattered over this time, and they rarely emerge in noticeable numbers. Annual cicada males also sing to attract females. The cicada killer wasp often captures these insects to provision its nest in the ground.
|Cicada eggs in tree branch.|
Periodical cicadas damage trees above and below ground. The most obvious damage is that caused by egg-laying in small twigs. This damage causes twigs to split, wither and die, causing a symptom called "flagging." Flagging is especially serious on young plants (four years or younger) because more of the branches are of the preferred size for oviposition, ¼- to ½-inch in diameter. Some of the more favored trees for oviposition include maple, oak, hickory, beech, ash, dogwood, hawthorn, magnolia, willow, apple, peach, cherry and pear. Flowers, vines and shrubs include Rose of Sharon, rose, raspberry, grape, black-eyed Susan, hollies, spirea, rhododendron, viburnum, junipers and arborvitae. More than 270 species of plants have been noted as hosts for egg-laying periodical cicadas.
Damage is also done by the nymphs that suck sap from roots. Prolonged feeding by nymphs on a tree's root system may reduce plant growth and fruit production. Cicadas do not bite or sting and have no known toxic chemicals. Adult cicadas are usually a nuisance by their sheer numbers and loud, piercing call. Cicadas have fluttered into automobiles and frightened drivers, leading to traffic accidents. Emerging cicadas may also be consumed by dogs and cats, but they cause no harm to these animals. These pets occasionally will consume so many of the cicadas that they regurgitate or become constipated.
|Flagging caused by oviposition.|
Periodical cicadas are especially damaging to young plants that have the most desirable branch size for egg-laying. This is especially important in tree nurseries. Large, established trees can withstand considerable flagging.
Cultural Control: Delay Tree Planting
If a periodical cicada emergence is predicted, it may be best to postpone new orchard plantings until the following spring. Home gardeners are encouraged to delay planting until late summer or fall, after the adult cicadas have died.
Cultural Control: Prevent Egg-Laying
Trees in small orchards or yards can be protected with nylon netting or cheesecloth during the egg-laying period. The netting should have a mesh of no less than ¼ inch and should be placed over the trees when the first male songs are heard. The netting should be tied to the trunk beneath the lower branches and can be removed after adult activity has ended. Eggs may also be removed by pruning out destroyed twigs.
Chemical Control: Not Recommended
Insecticide treatments are typically not recommended. However, if young trees are present and cicadas are in the area, treatment may be warranted. Registered products may be applied to deciduous trees and shrubs. These products should be applied prior to egg-laying. Blooming trees and plants should be avoided to reduce nontarget effects to honeybees. During persistent cicada activity, short residual activity pesticides will have to be applied every week or two until flight ceases. Before using any pesticide, always read the label, follow the directions and take safety precautions.
This fact sheet is a revision of HYG-2137.