The gypsy moth Lymantria dispar was introduced into North America from Europe in 1869 with the intent of producing silk and has spread as a pest of trees ever since. Its common hosts are oaks and aspens although hundreds of other tree species are also attacked.
The gypsy moth adult female is a white moth with wavy dark trim to her hind wings. Females are unable to fly. The males are brown with feathered antennae and a mottled look.
The larvae are distinctive because of its colorful spots, there are 5 pairs of blue spots behind the head followed by 6 pairs of red spots to the tail.
Eggs are laid on branches and trunks of trees but can be found in many other types of sheltered locations. About 500 eggs are laid in a mass covered with a peach-like fuzz. You can get a rash by contacting this fuzz with your bare skin. Unfortunately if eggs are laid on firewood and the wood is transported, the moth goes along for the ride.
The small larvae are dispersed by spining silk threads and waiting for the wind to lift them into the air and then once aloft they can spread to other areas. At first the larvae feed during the day but as they molt and grow larger, they switch to feeding at night
There are several steps to take short of applying pesticides to reduce numbers of moths.
Disparlure a sex pheromone can lure male moths into traps but this is mainly for detection and not control.
There are parasitic flies and beetles that attack gypsy moth larvae. Applying pesticides could reduce these natural control agents and make to goal of population reduction more difficult.
There is a virus that is effective in reducing outbreaks. The larvae eat the virus particles then die and their bodies disintegrate spreading the virus on foliage.
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