How Cicadas Develop

Using the blades of a curved, sawlike egg-laying apparatus on the end of the abdomen, the female cicada punctures the bark of a twig and makes a pocket in the wood. In the pocket she lays 24 to 28 eggs in 2 rows. She then moves forward, cuts another pocket, and lays more eggs. She continues this process until 5 to 20 pockets have been made in the twig. The pockets are placed close together in a straight row. Sometimes they form a continuous slit 2 or 3 inches long. Moving from one twig to another, a cicada lays a total of 400 to 600 eggs.

Section through egg punctures showing rows of eggs About 5 times natural size.

The eggs are laid in twigs and small branches of a wide variety of trees and plants. They hatch in 6 to 7 weeks. The immature insects are called nymphs.

The newly hatched nymphs fall to the ground and burrow until they find suitable roots, from which they suck juice. This is the beginning of a 17- or 13-year period of underground existence. Most of the nymphs are 18 to 24 inches beneath the surface.

Nymph ready for
transformation.		Adult beginning to
issue from nymphal skin.
Adult nearly free
from nymphal skin.		Freshly transformed
adult.

By spring of the 17th or 13th year the nymphs are fully grown. The transformation to the adult stage of the life cycle is soon to occur. Several weeks before emerging from the ground, the nymphs start burrowing upward. When they have burrowed to about an inch beneath the surface, they stop and await the proper time to continue.

When the proper night comes, in April or May, the nymphs leave the ground in vast numbers and head for upright objects. A tree is the ideal goal if it can be attained. But the transformation from nymph to adult cannot be delayed. If a tree is not within range, a bush or a weed, a blade of grass, or even a post or a telegraph pole, will do. The nymph secures a good hold on the object, splits its nymphal skin along the middle of the back, and laboriously works itself out. The job of shedding the nymphal skin is completed in an hour or less. The cicada is now an adult, but is soft and white. It hardens and becomes darker. In a few hours it is fully mature.

The insects mate within a week after becoming adults. A few days after mating, the females lay eggs.