According to the United States Forest Service(USFS), the gypsy moth is one of North America’s most devastating forest pests. After originally evolving in Europe and Asia for thousands of years, it was accidentally introduced around 1869 to the Boston area by E. Leopold Trouvelot, who was attempting to start a silkworm industry. This mistake has caused massive defoliation and damage to trees across the northeast region. Let’s take a closer look at the gypsy moth and what the future hold for regions impacted by this invasive caterpillar.
Identification – Gypsy Moth caterpillars change appearance as they grow. Young caterpillars are black or brown and about ¼ inch (.6 cm) in length. As they grow, bumps develop along their backs along with coarse, black hairs. Each of the 11 sections of a developed caterpillar will have two coloured spots, the first five pairs, blue, and the last six, red. Mature caterpillars can be as long as 2 ½ inches (6.35 cm).Source: The Gypsy Moth Guide
Damage – Tree damage is caused by the insect larvae, or caterpillars, which emerge from their eggs beginning in early spring and continuing through mid-May. The larvae move to the leaves of trees and begin to eat, mostly at night. Gypsy moth larvae grow by moulting and as is expected their appetite grows with each moult. The gypsy moth caterpillar is not a picky eater. It has a preference for the leaves of deciduous hardwood trees such as maple, elm, and particularly oak. Gypsy moths can also feed on apple, alder, birch, poplar and willow trees. As it grows it will also attack evergreens like pines and spruces. Depending on the degree of infestation, tree damage ranges from light to almost complete defoliation.
Management – Over the last 20 years, several millions of acres of forest land have been aerially sprayed with pesticides in order to suppress outbreak gypsy moth populations. In 1992, the USDA Forest Service began a pilot program to test the feasibility of slowing the spread (STS) of the gypsy moth in North America. STS pilot programs currently exist in North Carolina, Virginia, West Virginia, and Michigan. This map shows the slowed spread of this species. (USDA Forest Service)
Because the gypsy moth has many undesirable effects on trees and forests, efforts are made to manage the problem. Eradication and Slow the Spread are methods used to prevent or postpone the establishment of gypsy moth populations in portions of the country where it currently does not exist. Suppression, silviculture, and biological control are methods used to manage established gypsy moth populations.
Source: USDA Forest Service