Tree Insects - Gypsy Moths, History and Life Cycle
In 1870 an announcement was made by a well-known entomologist that a certain moth, ( Porthetria Dispar ), was accidentally introduced to New England. This was a serious pest of ornamentals and forest trees in Europe, and has no natural predator to keep it in balance.
Mr. Trouvelot lived at 27 Myrtle St. in Medford, Ma. , reported the escape of this pest. He was in search of a silk moth that would survive in America. He brought some eggs to his home where some adults or larvae escaped. Nothing was ever done about the report and that is why we have periodic gypsy moth problems today.
Larva emerging from egg case
Egg cases can be seen with naked eye in Fall prior to Spring hatch
The larvae hatch from early April to late May depending on the weather. The peak hatching period coinciding with the flowering of Shadbush Service Berry. The tiny larvae often remain on the egg mass for several days before climbing the trees to commence feeding. It spins a silken thread, suspends itself from a leaf, and is swayed by light breezes. Early stages like this one are referred to as the " Balloon " instars. They can be blown for miles during heavy winds.
As the larvae matures its feeding habits change. It feeds at night and descends from the tree to take refuge in the shade during the day. On heavily infested plants they will continue to feed through out the day, be it trees, shrubs, and even turf grass.
The larva stage lasts about six weeks, each week is referred to as an instars. After completing its feeding stage, the larva finds a sheltered place and pupates in a brownish-black pupil case. The adults hatch from early to mid July. Adult males are brown and can easily be seen flying around, females are white and can not fly far or of no real distance. Males seek the females at the top of the trees, mate, and fly off to die. After mating the females lay egg masses which will contain between 50-1000 larvae for the following year. Both adults will die without feeding after mating.
The only stage this insect can be controlled is the larvae. To try to control the eggs, or the adult, would be a waste of time and money. We are restricted as to what products we can apply to control this tenacious pest. Most properties will have adequate control with one treatment. In severe infestations more than one application maybe necessary. The material used will target 90% of the insects at the time of application. If high winds persist during heavy infestations, other gypsy moth larvae will blow or crawl onto your property.
Gypsy Moth Larva DO NOT MAKE TENTS
5Th Instar Larva
Every year we get calls from clients stating they have Gypsy Moth Caterpillars. Most of the time it is Eastern Tent Caterpillars, they see the tents in the crotches of the trees. Sometimes they just see many Caterpillars and they are Forest Tents.