The Gypsy Moth, one of the most damaging forest pests, continues to be a problem in Michigan. While infestation density fluctuates from year to year, Bloomfield Township is committed to controlling Gypsy Moth damage in our neighborhoods.
- Native to Europe, Asia and North Africa
- Moths are only seen in mid-summer
- Males moths are grayish-brown and can fly, females are larger, white with black marks and cannot fly
- Caterpillars have a yellow stripe on the back with blue and red dots
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:
Egg Mass – August to April
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.
Larvae (Caterpillar) – Early May into July
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.
Pupa – July and Early August
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.
Moth – Mid July to Early August
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.
Gypsy Moth in the United States
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. Gypsy Moth defoliates millions of acres of woodlands each year.
A mobile society helps to spread the moths via logs, pulpwood and wood chips, nursery stock, mobile homes, and outdoor household articles. Federal regulations prohibit the movement of such articles from the quarantined areas into or through areas outside of the quarantine. Further information concerning the articles requiring inspection and certification prior to movement can be found at this website.
Gypsy Moth in Michigan
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.
DNR Reports: Gypsy Moth Numbers Rising in Southern Michigan
Bloomfield Township’s Gypsy Moth Management Program
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.
The fungus, E maimaiga (a biological organism), has been cited as the key factor in the reduction of Gypsy Moth populations. Personnel from the Management Group apply the fungus to targeted trees in sites around the Township in the spring. If determined necessary another control measure, of selective ground spray application of Bacillus thuringiensis (Bt is a naturally occurring bacterium) by a private firm is combined with inoculation of the fungus. Concerns of residents are addressed through the season. A final report from the company is submitted in the winter for review and determination of future actions. The report outlines the program’s effectiveness including such issues as treatment timing, control measures and identification of improvement.
FREQUENTLY ASKED QUESTIONS
1. I’m not sure if it’s a Gypsy Moth, how can I tell?
It’s not a Gypsy Moth is if builds a cottony nest or web in trees; looks like a white moth that flies; is larger than a 50-cent piece or colorful; is a caterpillar with long stripes on its back or sides; or flies in springtime.
2. What do Gypsy Moths eat?
The Gypsy Moth is in the same category of insects as moths and butterflies that feeds on tree foliage. While oak tree leaves are the favorite food of a Gypsy Moth, they will feed on more than 600 species of trees, shrubs and vines. Michigan abounds with susceptible trees, including oak, birch, willow, crabapple, maple, aspen, basswood, linden and tamarack.
3. What is Bt?
It stands for Bacillus thuringiensis, a bacterium that occurs naturally in the soil and is known to be fatal to Gypsy Moth. A commercial preparation is used to reduce Gypsy Moth populations. Bt kills caterpillars, but it is not harmful to humans, fish, wild animals or plants.
Btk: One Management Option for Gypsy Moth
4. What can I do to help my trees against Gypsy Moth damage?
The best action to be taken is to keep your trees well watered, particularly during dry periods in the summer. Avoid wounding your trees with lawn mowers or other equipment. Avoid compacting the soil or damaging the root system of trees. Fertilize when appropriate. Sanitize by removing dead branches and stumps. When choosing new trees for the yard, aim for a diversity of plants.
5. What should I do if I suspect Gypsy Moth presence around my home?
If you suspect the presence of a Gypsy Moth, report problems to: Bloomfield Township Engineering & Environmental Services at 248-594-2800 or click here to report an environmental concern.
For More Information
Please contact the Bloomfield Township Engineering and Environmental Services Department by sending an Email. if you have questions about the material presented here. Please visit the following websites for more information on Gypsy Moths:
State of Michigan – Department of Agriculture
USDA Forest Service
USDA Animal and Plant Health Inspection Service (APHIS)
Bloomfield Township Gypsy Moth Report
Some images provided by: Perdue University, USDA Forest Service, US Dept. of Agriculture - Forest
Updated: June 2019