Much of West Virginia will receive a regular but not too welcome visitor this spring. Brood V of the periodical cicada, the so-called 17-year locust, will appear in large numbers in 40 counties in 1999.
The onslaught of this well known insect is always memorable because of its tremendous numbers, its incessant high-pitched sounds, and the loss of countless numbers of twigs and small branches. During its short aerial existence, it leaves very decisive signs of its presence in slits, which thickly fill the smaller twigs and branches of trees.
Growers worry that crops will be destroyed. However, the cicada does not feed on foliage of any kind. If the adult feeds at all, it does so by inserting its beak into bark and sucking juices. Besides making a lot of noise, about the only thing cicadas do in most places is prune the tips of branches and shrubs. It is their cousins--the likes of aphids, scale insects, and greenbugs-- that cause broad crop damage regionally and nationally.
The periodical cicada is a stout-bodied, black insect 1-1½ to 2 inches long. Its body has orange or orange-brown stripes, and the wings are membranous. The eyes and legs are red. It closely resembles the common "jar fly" or "dog-day fly" seen every year, except it is somewhat smaller and darker.
Myths abound
Long before Europeans came to North America, the American Indians observed the periodical cicada. Its appearance at 17-year intervals aroused their superstition and fear. The dark bars on their filmy wings resemble a "W," suggesting war to the superstitious.
The Pilgrims dubbed the cicada a "locust" on its first appearance to them at Plymouth, Mass., in 1634. It undoubtedly reminded the colonists of the migratory locust, a species of grasshopper that ruined crops in Egypt in Biblical times and still is a threat to crops in many parts of the world. To this day, some people still erroneously refer to cicadas as locusts.
Many stories are told of the sting of the cicada. All are false. The insect has no stinger. Young children might mistake the vibrations of the wings or the sharpness of the feet as a sting, but the cicada is not considered harmful. Some also claim that fruit is poisoned if stung by a cicada. This also is a myth.
Beyond the folklore, however, the cicada is one of the most intriguing of all insects on the American continent simply because of the curious features of its life history. The most remarkable of these peculiarities is its long period of underground existence, ranging from 13 to 17 years. In West Virginia, broods are all of the 17-year strain, and their last appearance was in 1982. So, get ready--they're due this year!
Bracing for the onslaught
After 17 years of living in underground tunnels, millions of cicadas will emerge from the earth in late May, as if by a predetermined signal. They'll undergo a startling transformation and fly to nearby trees and shrubs. From morning to night they will fill the air with their monotonous droning songs. In a few weeks, after mating and laying their eggs, they will die, leaving behind a multitude of injured twigs on the trees they have visited.
The eggs hatch in about six weeks, and the young cicadas drop to the ground, burrow into the soil, and attach to a suitable root. Here they remain, sucking sap from the roots of trees and shrubs for the next 17 years, until it is time for them to emerge. Because the young cicadas feed slowly, most trees survive.
For many people, it is the incessant singing of the adult periodical cicadas that makes their time above ground so annoying. The males produce five different sounds, but the call most commonly noted is best described as sounding like "farro." A second common call is a whirring sound. The female never breaks out in song, for she is voiceless. The adult cicada moves sluggishly, seldom takes food, and only occasionally resorts to flight.
Tree protection tactics
Damage associated with the cicada is caused not by feeding but by the egg-laying slits or punctures of the female. Twigs in which may egg slits have been made are often broken or partially broken from the branches. On young trees, this injury, if extensive, can set back normal growth. Wounds allow diseases to enter and provide shelter and feeding locations for other insects, such as scales and wooly apple aphid.
More than 250 species of trees and shrubs are subject to attack by the egg-laying female. However, she seems to show a preference for oak, maple, apple, dogwood, and nut trees. Mature forest trees can usually withstand this temporary harm because the cicada finds many twigs in forests in which to deposit eggs. Most at risk for damage is the lone fruit tree or seedling less than a foot tall.
To protect vulnerable trees, prune very lightly or not all all during the next few months. The female and her egg laying habits will damage twigs, weakening them so that many will break and fall from the tree. Wait till June or so to prune, when you can cut out, as far as is practical, the remaining badly damaged twigs and branches. With fertilization, you can stimulate these trees to a rapid, vigorous growth, so that the wounded places remaining may head more rapidly. Delayed pruning is especially important for fruit trees less than three years old.
Commercial fruit growers and nursery operators should make plans now to protect their plants. Cicadas could disfigure young orchard or nursery trees and make them less marketable. Most damage will be at the branch tips and will not affect fruit production.
By not planting small trees, shrubs, and ornamentals this spring, you can avoid damage caused by the female periodical cicada. You can protect existing plantings by covering them with open weave cloth, such as cheesecloth, mosquito netting, or tobacco shade cloth. Put the cloth in place as soon as the adult cicadas begin to appear, and keep the tree or shrub covered until most of them have died. Leave the cloth loose enough to allow for plant growth and sunlight. Be sure to tie the bottom closed or the cicadas will crawl up inside and lay eggs.
While some insecticides have made some control possible, they cannot completely protect the trees from damage. If you choose this method, follow the instructions and precautions on the label. Do not apply insecticides when there is a danger of drift or when honey bees or other pollinating insects are visiting plants.
The insecticide Sevin may be sprayed on the trees at about the time the cicada begins laying eggs. Apply the spray thoroughly to the trunk, scaffold limbs, and branches as damage prevention depends upon thorough coverage. For best results, it must be reapplied about every three to five days for four to six weeks. Spraying can stop when the singing stops.
And just when you think the singing will never stop, it does. As the droning finally ceases, West Virginians can take comfort in the certainty that the periodical cicada will not emerge again until 2016.
posted 2/15/99
