This job affords me the luxury of being outside, which I love. During these past two years, I’ve had the opportunity to observe and capture many moments of nature up close as I prune young trees, perform tree exams and/or water our newly planted trees. The Chronicle-Independent has graciously allowed me to begin sharing my various nature experiences and knowledge of trees with you. It is my hope that your knowledge be enriched by the many wonders right here in our fair city.
This inaugural Moment of Nature begins with an unlikely summertime celebrity and alien-looking creature that I have become fascinated and somewhat obsessed with: the cicada. The name of this unusual bug is a direct derivation of the Latin cicada, meaning “tree cricket.” Most common around here is the annual or dog-day cicada (Tibicen spp.) a signature element of our dog-days of summer, which, like each August, have descended upon us.
Cicadas sing in the heat of the day unlike true crickets who do their romancing at night! You know it’s going to be a hot day when the males call from their tree perches the distinct, weeee-oh, weeee-oh, weeee-oh, weeee-oh, weeee-oh…. that pierces the air at 8 o’clock in the morning. It seems like the hotter the better for them and they can have it.
Their noisy choruses are an unmistakable sign of the season and serves to attract the females. This is a risky business for the male because it also advertises his presence to predators! And there are lots of predators of cicadas. Many species of large birds, including such large raptors as the Mississippi kite (Ictinia mississippiensis), eat cicadas every chance they get. By emerging in great numbers over a short period of time, cicadas succeed year after year by overwhelming the predators with high enough populations to ensure the production of the next generation.
So, what exactly is a cicada and what does it do? Cicadas are members of the insect order Homoptera. Other insects in the same order are aphids, scales, leafhoppers, treehoppers and spittlebugs, all of which are commonly found in our southern landscapes. Cicadas are large (one and a half inches long), flying, plant-sucking insects that do not sting or bite humans but do have short, piercing/sucking mouthparts which resemble a hypodermic needle that is used to suck sap from plant and tree leaves.
National Geographic states that there are about 3,000 species of cicada around the world, and many of them remain unclassified to this day. They range from temperate to tropical climates where they are among the most widely recognized of all insects, mainly due to their size and unique sound. Cicadas are often called locusts, although they are unrelated to true locusts, which are a kind of grasshopper.
Male cicadas attract females by their characteristic songs, which at times can be quite annoying and rather loud. Some have been measured at 100 decibels at 20 yards away. According to Industrial Noise Control Inc., 100 decibels is as loud as an outboard motor, power lawn mower, motorcycle, farm tractor, jackhammer or a garbage truck!
After mating, the adult females begin to lay eggs by making slits in the twigs of various plants, mostly trees. Upon hatching, nymphs (a juvenile cicada) drop to the ground, burrow beneath the soil surface and spend the next two to five years feeding on root sap of various trees and shrubs. Oak trees seem to be a particular favorite and since we have so many here in town, it’s generally not too hard to find evidence of them in late July and August. The nymphs are tan in color, rather hunch-backed and have stout forelegs they use to dig through soil. To me, they look like an alien creature similar to what has been recreated on many sci-fi movies.
When full-grown, the nymphs emerge out of the ground at night, creating a hole the size of a jumbo magic marker. They crawl up a nearby tree or wall and the skin splits along the back. What appears is a big-headed, bulging-eyed, green and winged adult that hangs from the plant for several hours. During this time, the newly morphed creature rests as its wings and body harden off and then it flies away. What’s left behind is the shell of their former shelf, literally. If I were 10 years old again, the nymph shells would be great to scare a younger sibling with -- if I had a younger sibling! I did recently learn, though, from Katherine Richardson, the Camden archives assistant director, that the nymphs shell or skeleton will stick or cling to just about anything. Upon learning this I stuck one on my safety vest and then on my hat and walked around all afternoon and no one noticed. If they did, they didn’t say anything. Wonder why? To my delight, I have found as many as a dozen such skeletons stuck to the bark, twigs and leaves of one of our newly planted street trees. Ok, yes I’m a bit odd about all of this, but these insects are really cool when you see them up close.
For the most part, the population of annual cicadas is not considered a nuisance unlike its cousin the periodic cicada (Magicicada spp.) whose synchronized emergence in the thousands always makes headlines. Most of their life cycle is spent underground, appearing for just a few months every 13 to 17 years. Adult periodic cicadas have black bodies and distinctive red eyes -- talk about a bizarre looking insect, they are it.
In general, cicadas are not considered a major plant pest and usually do only minor damage. By September, you may see evidence of their egg-laying activities; small dead twigs will appear in the canopy of a tree. This is called ‘flagging’ which during some years can be numerous but it is not considered a serious health threat nor will it kill a tree. Other than that, their role in the cycle of life is to make a good food source for birds and other animals and to remind us that our hot summer is almost to an end.
Research sources: Colorado State University Extension, Texas A&M University AgriLife Extension, Wikipedia, Great Plains Nature Center, About.Com Insects and InsectSingers.Com