If you live along the east coast you have probably heard the dire forecast for the latest outbreak of periodic cicadas. You are going to be overrun with cicadas that outnumber humans by hundreds to one. Or, you are going to be unable to hear anything but cicadas when you step outdoors. In reality, most people along the east coast will not even notice a single cicada.
Almost every area of the country has one of the several annual cicada species that hatch every year, (they actually live between two and eight years). They just don't have the synchronized schedule like periodic cicadas. They also tend to hatch later in the summer. There are at least seven species of periodic cicadas with four having 13-year live spans and three having 17-year life spans. Most of the species are identified by entomologists by their songs.
Each species is further divided into broods that hatch all at once. This year's 17-year cicada is brood II out of 12 broods of 17-year cicadas. They cover parts of nine states, from the North Carolina to New York and are nicknamed the East Coast Brood.
The brood II periodic adults that are hatching now were born in 1996 and there won't be adults again until 2030. The grub stage of the cicada is called a nymph. They live underground and suck on plant roots. They undergo five stages of maturing and change from about the size of an ant to about as big as the two to three inch long adults. They can dig down many feet into the soil, and when they emerge from the soil they leave behind a half-inch diameter hole that provides good soil aeration. They all seem to hatch from the ground at the same time because they need a body temperature of over 64 degrees to be able to hatch. They spend most of the first week hiding in vegetation before hardening their exoskeleton.
Cicadas are sometimes called locusts, but locusts are a type of grasshopper and once you see a cicada, you will know they are not grasshoppers. As an adult, they are only capable of sucking plant juices instead of chewing plants like grasshoppers. They need live plants to suck on or else they will die within a few hours. They can't jump like a grasshopper. They are weak flyers, but they fly better than a grasshopper.
Cicada sexes are easy to identify. The males have a tymbal membrane on each side of the hollow abdomen right behind the attachment of the back wing that makes the song. Females have a long ovipositor that is used to lay eggs in plant twigs.
If a large number of adults are on a small tree, they may damage it by sucking too much water out of it. Females cause the majority of plant damage that can harm small or newly planted trees. She lays her eggs in the soft tissue at the end of the new twigs. She will lay about twenty at a time in each inch long slit. She can lay over six hundred eggs altogether. The end of the branch will often die and break so that it hangs down and the leaves turn brown. This is called flagging. In a few weeks, you will be able to see which twigs have been damaged and then you can prune them back properly and remove the flag.
Mature trees and shrubs will survive an outbreak of period cicadas just fine. Cicadas are nature's way of pruning big trees every so often. Newly planted trees can be protected by covering them with cloth for the few weeks that the females are laying eggs. Annual cicadas that occur later in the summer all over the country will lay their eggs the same way and the same flagging will occur. The same treatments apply, but there are so few at one time that most people don't notice the flags.
The eggs in the twigs will hatch in about two months and the tiny nymph will drop to the ground and begin looking for plant roots to live on. If you have new small trees planted under mature trees that develop lots of flags, you may want to apply a grub control around the small tree in a few weeks after the flags appear. Otherwise no grub control is necessary.
All cicadas are harmless to people and pets unless they eat too many of them. Yes, people eat cicadas. Even people not on reality television shows. Some people turn out to be allergic to them, so don't eat too many at once. Some dogs will eat too many at once and get sick or constipated, since it can't digest the cicada's exoskeleton. If you see your dog eating them, leave it outside for a while.
Birds will find the cicadas a wonderful food to feed their babies, and the local songbird population will have a baby boom this summer. In spite of many predators, many cicadas seem to survive. There may be tens of thousands per acre. The high populations will be in areas that were wooded 17 years ago. Many urban locations won't see any. For a few short weeks, it may difficult to have outdoor activities, including weddings, ball games and practically anything else as the noise the males make can be deafening.
Email questions to Jeff Rugg at email@example.com.