Identify the Gypsy Moth

The Gypsy moth passes through four stages: egg, caterpillar, pupa, and adult moth. Only the caterpillars damage trees and shrubs in the spring of the year, and may attack hundreds of host plants.

Damage from feeding caterpillars can be severe. They may completely defoliating large areas of urban and woodland areas. Nearly every landscape tree and shrub is on the Gypsy moth's menu.

The following information will help you identify the Gypsy moth. If you suspect Gypsy moth in your area, please let us know by filling out the Contact Us page.

How to Identify the Eggmass:

Gypsy moth egg masses are laid on branches and trunks of trees, or may be laid in any sheltered area, and on any outdoor article. Egg masses can be moved by unspecting people for this reason.

(Click on the pictures for a larger view.)

It is quite possible to move Gypsy moth egg masses thousands of miles that have been laid on cars, campers, potted plants, lawnchairs, firewood, or any other outdoor article.

Link: U.S. Federal quarantined areas for Gypsy moth.

There is a Federal Law, as well as State Laws that prohibit the movement of Gypsy moth articles from regulated areas.

Egg masses are buff colored when first laid, but may bleach out over the winter months when exposed to direct sunlight and weathering.

Egg masses may vary in shape and size, but generally range about the size of a quarter to a fifty cent piece. They may contain from 30 to several hundred individual eggs, depending on the nutritional diet of the female caterpillar during it's development.

How to Identify the Caterpillar:

The hatching of Gypsy moth eggs coincide with the budding of most hardwood trees. Caterpillars emerge from the egg masses early spring, or about the same time oak leaves are 1/3 expanded. Usually this is in the month of May depending on warm weather.

Caterpillars or larvae, develop by going through a series of progressive molts by which they increase in size. The first caterpillar stage is small enough where strands of silk may be caught by the wind, thereby transporting larvae to new areas.

Older larvae have five pairs of raised blue spots behind their head, and six pairs of raised brick-red spots along their back. These spots indicate the Gypsy moth caterpillar.

(Click on the pictures for a larger view.)

Larvae have large "eyespots" on the front of their heads, that are thought to help ward off predators. These eyespots are also indicative of the Gypsy moth caterpillar.

How to Identify the Pupa or Cocoon:

Caterpillars pupate into the adult moth during mid-summer in the months of June and early July. Pupation may last from 7 to 14 days.

Pupa are dark brown with only a few orange-yellow hairs, and may be found in any sheltered area where the caterpillars have rested.

Pupae may be found exposed on trees, the sides of buildings, and also in hard to find places. They can be moved easily by unsuspecting people on any outdoor article, motor vehicle, or camper trailer.

How to Identify the Adult Moths:

When heavy egg-laden female moths emerge from the pupa, they emit a chemical "pheromone" to attract the male moth. Since the female moths are so much larger than the male, they are not capable of flight.

Male moths on the other hand are very capable of flight. They follow the pheromone plume emitted by the female moth by using their feather-like antennae to pick up the chemical signal.

Female moths will lay egg masses in locations most convenient to them, which may include being deposited on any outdoor article. Egg masses are often found hidden underneath bark flakes on trees, or may be completely exposed and easily found.

The egg mass will remain dormant through the fall and winter. The next generation of Gypsy moth caterpillars will hatch the following spring.