A mature caterpillar may eat several leaves daily. In heavily infested areas, whole trees may be virtually stripped overnight. Although defoliation figures change from year to year, thousands of acres of woodlands are defoliated every summer. For example, during 1988, gypsy moth caterpillars defoliated approximately one million acres of trees, compared with 464,451 acres in 1975. In 1988, about 100,000 acres were defoliated in Michigan.
Second favorites are the evergreen varieties.
When insect populations are high, caterpillars have been known to attack ornamentals and almost every leafy plant in the forest. A. Evergreens frequently die when totally defoliated, since they are unable to replace their needles. Most other tree species will grow new leaves during the same season, but may be left in a weakened condition, susceptible to secondary attack by other insects and tree diseases. Two or three years of consecutive defoliations may kill some hardwood species. For instance, the forest makeup of New England is not the same now as it was 100 years ago when gypsy moths first invaded that region.