Gypsy Moth

The Gypsy Moth is in the same category of insects as moths and butterflies. This group of insects is known for both their beauty and their destructive nature. The four life stages of the Gypsy Moth and the time of appearance include:

Most of the yearly cycle of the Gypsy Moth is spent in the egg stage. The egg masses survive the winter insulated by the covering of hair. The egg stage in Michigan usually runs from August to April. The egg mass in late summer and early fall appears to be a dark tan to light brown turning light tan to gray in color. An individual egg mass may contain anywhere from 100 to 1,200 eggs. The egg masses will lie on tree bark and on many natural and manmade objects that are commonly found outside.

Hatching of the larvae is influenced by spring warming trends with most eggs hatching within a week. Larvae are approximately 1/8 inch at hatching and grow to about 2 to 3 inches long before pupation.

As the larvae move up the tree, a thin line of silk is produced behind them. When the wind picks up the thread the young larvae are moved to another location. When resting, the young larvae can be found on the underside of the leaf along the mid-rib of a leaf.

The larvae reach maturity between mid-June and early July and then they enter the pupal stage. This is the stage during which larvae change into adults or moths. Pupation lasts from 7 to 14 days. When population numbers are sparse, pupation can take place under flaps of bark, in crevices, under branches, on the ground, and in other places where larvae rest.

The adult Gypsy Moth emerges from the pupal shell and contains mature eggs or sperm so mating can occur immediately. The adult form does not feed and usually lives only about a week.

The Gypsy Moth is native to Europe, Asia and North Africa. In 1869 a scientist in Medford, Massachusetts, introduced the European strain of the gypsy moth into the United States. He wanted to breed them with other moths and develop a new strain of silk-producing caterpillars. The experiment failed and some of the caterpillars escaped, finding this new country to their liking because of its adequate food supply and few natural enemies.

Since then, Gypsy Moths have spread through the northeastern states, North Carolina, Washington and California affecting over 19 states. Click here for the most current map illustrating the Gypsy Moth spread. Gypsy Moth defoliates millions of acres of woodlands each year.

Gypsy Moth is an episodic organism that can exist at low populations. Low populations increase and become high populations, which crash and the episode begins over. Since the mid 1950’s Michigan has battled the Gypsy Moths. Major defoliation events have taken place since the mid 1980’s. Significant Gypsy Moth population and defoliation first occurred in the Clare-Midland area and moved up the central portion of the Lower Peninsula. In the early 1990’s populations moved east, west and then south in Michigan into the Grand Rapids and Flint areas. By the mid-1990’s populations began popping up in the metropolitan Detroit area.

As new infestations were discovered, regulatory policy shifted from trying to eradicate the gypsy moth to a policy of containment in the late 1970s. Today, Gypsy Moth can be found throughout all of Michigan including the Upper Peninsula.

The Township has assumed primary responsibility for Gypsy Moth management. Since 1993 Bloomfield Township, together with the National Gypsy Moth Management Group, has implemented an integrated pest management approach to reduce and contain the Gypsy Moth problem. The goal is to control the pest and minimize the economic, social and environmental costs. Components of the program include: public education, intensive biological monitoring and treatment plus evaluation.

Annually, National Gypsy Moth Management Group personnel collect data from biological surveys. Such surveys are conducted at permanently established survey locations to determine Gypsy Moth population, density and health, susceptibility and vulnerability of trees and infestation trends. This yellow tag is placed on trees that grow within the survey areas.