The best thing for homeowners to do is keep an eye out for gypsy moths on their property.  You can tell if you have a gypsy moth problem if you find egg masses, caterpillars, or signs of defoliation on their favored species, like white oaks.
 
Healthy new egg masses will be the size of a quarter or larger, buff or tan in color, and firm to the touch. New eggs will make a popping noise when squeezed between your fingernails.  Old egg masses from last year or even earlier are soft to the touch and usually lighter in color. They also don’t make any noise when they are squished. You will find egg masses on tree bark, and also under the eaves of buildings, or in protected areas on patio furniture, fences, low walls, and other man made items.  It is very important to check items stored outdoors if you are moving or taking them on vacation with you, so that gypsy moths don’ t hitch a ride to a new place.
 
Gypsy moth caterpillars have long hairs and develop colored dots in rows down their backs as they grow.  The first five sets are always blue, while the last six are red.  There are many different caterpillars that feed on tree leaves and telling them apart can be difficult. Check out this website from Virginia Tech to help distinguish between native caterpillars and gypsy moths.
 
Defoliation looks like buckshot holes in the leaves when feeding is relatively light.  When population levels are high, entire trees can be stripped of their leaves.  Gypsy moths like oak trees best, but also favor aspen, apple, basswood, willow, gray birch, white birch, river birch, box elder, hawthorn, and witch hazel.  Once their favorite foods are all gone, gypsy moth caterpillars will feed on over 300 species of trees. A complete listing of trees and their susceptibility to gypsy moth can be found here
 
Give us a call if you find any egg masses or defoliation! Prince William County Mosquito & Forest Pest Management Branch monitors for gypsy moths, and your information will help us determine how large their populations are.  Population levels are used to determine whether or not the county will be sprayed to help control the damage.
 
 

 Contact Us

 
14879 Dumfries Road
Manassas, VA 20112
Phone: 703-792-6279
Fax: 703-791-3092
Email: gypsymothmosquito@pwcgov.org