Cicadas are large, stout insects. They have round bulging eyes on the corners of their heads, and short, bristly antennae. They have sucking mouthparts that attach at the base of their head.
Adults have four wings that they hold folded over their backs like the roof of a house. They also have special panels on the sides of their bodies called "tymbals." They vibrate these very fast to make loud sounds.
Young cicadas are called nymphs. They have no wings, and their front legs have thick claws for burrowing.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Pretty much any animal that eats insects will eat a cicada if it can catch one. Cicadas don't have many defenses. Nymphs hide deep in the soil. Adults will fly from danger if they can, and if caught make a very loud buzzing sound that may surprise predators. When millions of cicadas emerge at once, they overwhelm their predators: there are so many that the predators can't eat them all, and many cicadas survive.
Newly-hatched cicadas climb or drop down to the ground from the branch their egg was in. They burrow into the ground and start feeding on the plant juices in roots. As they grow they shed their exoskeleton several times. They sometimes spend many years in the soil before they are finished growing. For some species it takes 13 years, others take 17, and some take less, but nobody knows exactly how long.
When they are mature, they climb out of the ground and complete one final molt. They emerge as an adult cicada with wings, and fly away to find a mate. Once they become an adult they stop growing and do not molt again.
Some of the species that take 13 or 17 years all come out of the ground at one time. There can be millions of adult cicadas flying around at that time.