Prepare for upcoming, annual cicada invasion
By now, you may have heard that there is going to be a major outbreak of cicadas in the Midwest and Eastern-seaboard states. 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.
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 lives and three having 17-year life spans. Most of the species are identified by entomologists by their songs.
The individual hatching of periodic cicadas are known as broods. There are 12 broods of the 17-year cicada and three broods of the 13-year cicada. This year’s brood is number 13 and is one of the northernmost broods. There is a different brood hatching almost every year in some part of the country. Although, there are occasional hatchings of several thousand in seemingly random populations in odd years.
The periodic adults that are hatching now were born in 1990. 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 2- to 3-inch-long adults. They can dig down many feet into the soil, and when they emerge from the soil, they leave behind a 1/2-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 more than 64 degrees to be able to hatch. They can spend almost the first week hiding in vegetation before hardening their exoskeleton.
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 twigs. She will lay about 20 at a time in each inch-long slit. She can lay over 600 eggs altogether. The end of the branch will often die and break partially off 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 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, so the same treatments apply.
The eggs 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.
All cicadas are harmless to people and pets unless they eat too many of them. Yes, people eat cicadas. Even people not on goofy 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. So, if you see your dog eating them, leave it outside for a while.
In spite of many opportunistic predators, most cicadas seem to survive. This allows for an extremely large number of individuals, up to tens of thousands per acre. For a few short weeks, it may be difficult to have outdoor activities, including weddings, ball games and practically anything else.
A fungal disease can infect the adults as they emerge. It does not immediately kill the cicada, but does spread among the other cicadas as they mingle. Due to a variety of conditions, some cicadas will fail to fully emerge as adults, or may end up with wings so deformed that they can’t fly. Someday, enough information may be gathered that a natural treatment can be developed so that the population can be reduced. In the meantime, they won’t do too much harm and you won’t have to worry about this brood for another 17 years.