Insects can have important effects on forest ecosystems. A variety of insects and diseases affect tree health in southern New England. In particular, two insects -- the pear thrip and gypsy moth – are of concern in our study area. As evidenced in the graphs, the effects of these insect outbreaks is reflected in the growth rates of most of the trees sampled.
Pear thrips feed on the expanding tree buds, affecting sugar maple tree growth rates. Damage by this insect occurred in Connecticut in 1988 and can be seen in the tree core samples taken. Pear thrips are also a vector for a fungus which enters the leaf’s wound created by the thrip. This leads to necrosis, deformity, and leaf tissue discoloration. Of our study trees, sugar maples are most susceptible to pear thrips. Although pesticides have been used to control pear thrips in orchards, there are no chemical controls registered for use against this insect in forest stands. Further information is needed before control strategies can be developed for forested areas.
The European gypsy moth (Lymantria dispar) was accidentally introduced to New England in the mid 1880s. Prior to the 1940s, the species was largely confined to New England but has now established viable populations as far south as Virginia and North Carolina. The gypsy moth is a serious defoliator of hardwoods and shrubs, and forests of the eastern U.S. have been significantly affected by this pest. During a particularly serious outbreak in 1980 and 1981, a total of 1,754,429 acres were defoliated in Connecticut.
The gypsy moth larvae generally prefers oak, poplar, birch and willow
leaves, but will attack other tree species as their preferred food becomes
scarce. During the 1980-81 gypsy moth attack, oaks were attacked
first followed by the other hardwood species. Totoket Mt. was totally
defoliated in the 1981 outbreak (hardwood).