You know summer has arrived when cicadas start “singing”. Most people hear these strange-looking insects more often than they see them, but if you keep your eyes open you may be able to spot a cicada or a cast-off skin on a plant or twig.
If you find a singing cicada, you will be able to see his body vibrate each time he emits his song. Only the males sing in an effort to attract mates.
A male cicada does not have vocal chords, but instead sings by vibrating a pair of membranes near the base of his body. The membranes are attached to powerful muscles that very rapidly jerk them, causing the membranes to snap in and out and make the high-pitched shrilly whine that we hear on most summer days.
After a female cicada has mated with a male, she will use a sharp, spear-like egg-laying tube known as an ovipositor to make a slit in a twig of a tree. She will then stay still for several moments while eggs are pushed through the tube and into a pocket inside the wood. She will repeat this scenario many times, laying perhaps 500 eggs by the time she dies.
In several weeks the eggs will hatch, and the immature cicadas, known as nymphs, will crawl about on the twigs. You might be able to witness this if every day you check a twig that you know contains eggs.
The slits are quite obvious. They are surrounded by fibers along the edges and they are not very long. Look for them on the ends of live branches or twigs of small trees (the twigs eventually die off because the nutrient flow has been severed).
Nymphs do not remain above ground for long. They drop off of the twigs and search for a crack in the earth. As soon as they find one, they start digging down and disappear.
They will not see the light of day again for a year or more, depending upon the species. They spend this time feeding upon the roots of trees, sucking sap, and growing ever larger.
Finally, a species’ built-in time-clock will alert the nymphs to start heading upwards. But when a nymph emerges from the soil, it is not ready to mate.
Each nymph must first find a sturdy plant stem, or a shrub or tree, to climb up and anchor its feet on. It then waits for a seam to open along its back so that the adult cicada inside the old skin can get out.
Soon the cast-off skins of numerous cicadas cling to herbaceous and woody plants and the adult insects are high in the trees, ready to mate. It is then that we begin to hear the singing that is truly a sound of summer, with each species belting out a different song.
Naturalist Marlene A. Condon is the author/photographer of The Nature-friendly Garden: Creating a Backyard Haven for Plants, Wildlife, and People (Stackpole Books; information at www.marlenecondon.com). If you have a question about plants or animals, or gardening in a nature-friendly manner, send it to [email protected] and please watch for an answer in this paper.
