GYPSY MOTH

(Lymantria dispar), member of the tussock moth family Liparidae (order Lepidoptera) that is a serious pest of deciduous and evergreen trees. The European strain was introduced into eastern North America about 1869, and by 1889 it had become a serious pest of forest and fruit trees. (Damage is less severe in Europe, where the moth has several natural enemies.) The heavy-bodied, weak-flying female moth is white with black zigzag markings and has a wingspan of 38 to 50 mm (1.5 to 2 inches). The smaller, darker male is a stronger flier. Eggs deposited in clusters during July are covered with a mass of buff-coloured hair from the female's abdomen; they hatch the following spring. The flattened, pale brown larvae, with tufts of stiff brown and yellow hairs on their sides, grow to 50 mm and are voracious feeders, often completely stripping trees of their leaves in several weeks. The adult moth emerges from a chrysalis after about 10 days, completing the annual generation. The Asian gypsy moth has a wingspan of about 90 mm. It poses an even greater threat than its European relative because the female can fly, enabling it to spread quickly, and the larvae, which range in colour from light to dark brown, will eat the leaves of coniferous as well as deciduous trees. It has defoliated millions of hectares of trees in Russia and China and was introduced into northwestern North America in 1991. Insecticidal spraying of eggs and young larvae remains the most effective means of controlling gypsy moths.