Life Cycle and Biology

Life Cycle and Biology

The female gypsy moth (see below) lays an egg mass, covering it with body hairs to act as insulation and to help protect the eggs from predators. Shortly after the female gypsy moth lays the egg mass, she dies, and the eggs wait out the long winter until temperatures rise in the spring and a hatch begins.

				(Egg Mass)
(Female Moth)

Upon hatching, the caterpillars go through five or six instars. Newly hatched caterpillars are buff-colored but within a few hours turn black. The head capsule is always black.

Within each instar, the caterpillars grow in length and width, but the size of the head capsule does not change. As the caterpillars approach the next instar, the head capsule appears small in relation to the body width. After the molt, during which time the old head capsule is shed along with the skin, the new head capsule appears large in relation to the body.

New second instar caterpillars are about one-half-inch long and nearly black, with irregularly shaped yellow marks visible on the upper body surface. Older caterpillars (fourth, fifth and sixth instars) begin to develop distinct color markings on their backs: five pairs of blue dots followed by six pairs of red dots.

The time between instars varies according to outdoor conditions. The cycle is likely to be completed in less than 60 days, with most of that time taken up by the caterpillar stage. Pupation takes seven to ten days, then the adults emerge. Adult gypsy moths live up to two weeks. The female moth mates and lays 50 to 1,500 eggs in one mass.

(Calendar of Gypsy Moth Activities)

Related Extension Bulletins

E-2303 - Gypsy Moth in Michigan: Homeowner's Guide
E-2299 - A Comparison of the Gypsy Moth, Eastern Tent, and Forest Tent Caterpillars

Document Author(s): Program Staff
Revised: September 11, 1997
URL: http://www.ent.msu.edu/gypsyed/docs/lifecycle.html