One species of cicadas, small dark insects about 1 to 2 inches long with heavy bodies and thin wings, holds the insect record for the most unusual life cycle. The cicada, also called the 17 year-locust, spends 17 years sleeping in the ground, comes out for five weeks in the sun, then it dies!
Scientists do not know why this little insect takes 17 years to develop and grow. But they do know what happens during that 17-year cycle.
The female cicada first selects a twig of a tree or shrub to her liking Then she makes a small hole on that twig, using a saw-like organ near the tip of her abdomen. She places her eggs in this hole. In a few weeks, the eggs hatch into young cicadas, called nymphs. The nymphs now go in search of food. They drop down to the ground, burrow into holes, and attach themselves to roots. For 17 years, they remain there, almost in a sleep, feeding on the sap of the roots.
When they are full grown, some sort of mysterious alarm clock seems to awaken them and send them out into the sunlight. They climb up the trunk of a tree, shed their skin, and come out as adult cicadas. For the next five weeks, they fly about, feed, and lay eggs. Then they die.
Male cicadas, who make the shrill sounds heard in fields and woods, have tiny drum-like plates vibrated by muscles that never seem to stop working!
