State Department of Agriculture officials weren't surprised by the caterpillar's return, said John Kegg, chief of the department's Bureau of Plant, Pest and Disease Control. Forsell said damage from the caterpillar last year was only 1,380 acres in six municipalities in Salem and Burlington counties. The gypsy moth caterpillar was unintentionally introduced into the United States from France in the late 1800s. The insect can kill a needleleaf tree in one pass. It also can make a broadleaf tree suffer several years before killing it.
Scientists say the caterpillar mostly enjoys oak tree leaves.
The good news is that the assault is nearly over for this spring. That's because the caterpillars are getting ready to become pupae. They will emerge as moths after spending two weeks in the cocoon. But there could be a problem next year because although the moths don't feed off trees, they will mate and lay eggs. Those eggs next spring will hatch as new caterpillars.