By DAVID GREEN
It’s the familiar age-old insect story for cicadas: from egg to larva to nymph to adult. Then mate and die.
Hold on a minute; it’s not quite that simple for a cicada.
There’s also the long chapter about hanging out underground for a couple of years. There’s that part about climbing up trees to break out of their exoskeletons. There’s the habit of climbing high into trees and filling the summer air with their “singing.”
Admit it; the cicada is a remarkable animal.
You know it’s cicada season when the brown husks begin appearing on the sides of trees and the loud whirring sound is heard in the latter part of summer. It’s the sound of the dog day cicada or as it’s sometimes called, the harvest fly.
The cicada has an interesting life cycle. First comes the egg that’s deposited into the twigs of trees. When they hatch, the larvae are said to resemble a wriggly grain of rice. They feed on the branch for a while and eventually drop to the ground.
The larva then digs into the dirt until it encounters a tree root. It sucks sap from the root occasionally for at least two years, and when the time is right, the larva tunnels to the surface and climbs up tree, a wooden fence or the bricks of a porch.
They anchor themselves with their legs, the back of their shell begins to split open. Within an hour or so, the adult cicada emerges. If all goes right, the wings that were folded compactly within the shell are pumped with fluid and grow to a length of almost two inches.
The males fly high into trees and begin making the sound that attracts a female. Each species gives off a different call, and the sound varies with temperature and the time of day.
The noise isn’t a vocalization. They’re produced by specialized organs called tymbals that are found only on the males. The sound is among the loudest produced by any insect.
After mating, females use a sawlike organ to cut a slit in a twig and deposit the eggs. After six or seven weeks, the eggs hatch and the cycle begins again.
Cicadas are in the same insect order as aphids, scale insects, leafhoppers and others. Although they look fierce when buzzing through the air, they don’t sting and they do very little damage to trees.
There are more than 160 species of cicadas identified north of the Mexican border in North America. Several live in this area, including a few species of the dog day cicada that area heard every year. Although the nymphs spend at least two years underground, there are always some emerging every year.
Not so with the periodical cicadas. They follow underground cycles of either 13 or 17 years. When it’s time for their emergence, they arrive by the tens of thousands.
Schedules of the emergence patterns are listed and Michigan’s next showing should come in 2004.
After all that time underground, the life cycle of a cicada is really very short. The nymph burrows to the surface, an adult emerges and lives for only two to six weeks.
Appreciate the sound of the cicada. It won’t be here for long.– Sept. 4, 2002