As we make the transition from spring into summer, the wildflowers are fading, flowering trees and shrubs are ablaze in color, and the mosquitoes, deer flies, and other insects are making their presence known in one way or the other. We are all too familiar with the biting and blood sucking insects that cause us so much irritation, but there is another insect that can almost drive people to insanity due to the constant “saw like” drowning; the periodical cicada. Once every 17 years these noisy insects make their appearance.
There are seven species of periodical cicadas in the genus Magicicada. They are divided into groups called Broods. This year will mark the emergence of Brood V. The brood number is usually written in Roman numerals. Charles Marlatt, an entomologist working for the Department of Agriculture, designated that all the cicadas that emerged in 1893 and at 17-year intervals thereafter as Brood I. The cicadas that emerged in 1894 were called Brood II and so on. Periodical Cicadae are distinguished by bright red/orange eyes and black bodies with orange markings. Periodical cicadas are often incorrectly called locusts. Locusts are grasshoppers and cicadas are more closely related to aphids than grasshoppers. The term locust started to be used around 1715 in the English colonies, when citizens tried to make sense of the cicada emergences by equating them with the biblical plagues. In 1956 the XIII brood emerged and estimates were upwards of 1,500,000 cicadas per acre! Adults emerge from April through July, depending upon species and locality. This year it is estimated that the cicadae will emerge in late May. Portage County will see an average emergence, while Summit County will see a heavy emergence.
Cicadas don’t bite or sting so they don’t pose any danger to humans. They do have prickly feet and a beak which can pinch or scratch. However, they can damage small trees and shrubs when the females deposit their eggs. In order to prevent your newly-planted tree or shrub from damage you can wrap netting around them, spray them off with a hose, or manually pick them off with your hand. Because adult cicadas don’t eat, don’t bother with pesticides, you will be wasting your money.
As indicated earlier, in late May when the ground tempture is at least 64 degrees, the cicadas emerge from the ground as nymphs. Nymphs climb the nearest available tree, and begin to shed their exoskeleton. Free of their old skin, their wings will inflate with fluid and their new skin can harden. Once their new wings and body are ready, they can begin their brief adult life. Adults can live for 5 to 6 weeks. Adult cicadas spend their time in trees looking for a mate.
The life cycle of the cicadae is very simple. The males make their “mating call” by flexing their tymbals, which are drum-like organs found in their abdomens. Small muscles rapidly pull the tymbals in and out of shape like a child’s click-toy. The sound is intensifed by the cicada’s mostly hollow abdomen. Records in Floridia indicate that some cicadas can produce sounds of between 108-120 decibles. The pain threshold for humans is 120-130 Decibels. Any sound above 85 decibles can cause hearing loss. Just remember, human speech is only registered at about 25-35 decibels. Female cicadas also make a sound by flicking their wings, but it isn’t the same intensity as the males. After mating, females insert clusters of eggs into grooves at the ends of twigs and small branches using a saw-like egg laying structure called an ovipositor. These grooves can kill small branches. When the branches die and leaves turn brown, it is called flagging, a common sight in early August after the emergence of the adult brood. In 6 to 7 weeks, small nymphs hatch from the eggs and drop to the ground. They burrow into the soil, seeking tree roots. They suck fluids from the roots for food, but this does not harm the tree in any way. As they molt through several stages of growth called instars, they may burrow several feet down.
Cicadas serve a number of purposes. They aid their host trees by aerating the soil when they emerge, as well as trimming weaker branches when they lay their eggs. They also form a vital link in the food chain between trees and literally hundreds of carnivores and omnivores, including: squirrels, birds, toads, raccoons, possums, other insects, and people.
Another cicada which occurs every year is the annual or dog day cicada, genus Tibicen, which varies in size and color according to species. They do not emerge in the enormous numbers like their periodical cicadas. Dog day cicadas have prominent black bulging eyes and semi-transparent wings held roof-like over their large bodies. The larger species are about 1-5/8-inch-long and 1/2-inch wide with brown or green, black and white body markings.
Get your ear plugs now. You are going to need them!