Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 315

833

Lymantria dispar (Linnaeus) ( 833-835 )
Gypsy moth
An important and often destructive pest of trees and
shrubs, especially oak ( Quercus ) but also beech ( Fagus
sylvatica ), common hazel ( Corylus avellana ),
hornbeam ( Carpinus betulus ) and many others.
Palaearctic. Widely distributed in mainland Europe,
from mid-Sweden to the Mediterranean; extinct in
Britain but has occurred in recent years. An introduced
pest in North America.

DESCRIPTION
Adult female: 50-70 mm wingspan; wings mainly
brownish white, with irregular greyish to blackish
cross-markings. Adult male: 35-50 mm wingspan;
wings greyish brown, with blackish markings; antennae
strongly bipectinate. Larva: up to 75 mm long; grey to
greyish yellow, with darker markings; body with long,
brown hairs arising from prominent verrucae; verrcuae
on the thoracic segments and first two abdominal
segments blue, those on the third to eighth abdominal
segments brownish red.

833 Female gypsy moth ( Lymantria dispar ).

834

LIFE HISTORY
Adults occur from late July onwards, the flight period
varying according to local conditions. The females do
not fly but crawl about on the trunks and branches of
host trees, sometimes also gliding to the ground from
the tops of tall trees. Adult males are most active at mid-
day, flying about rapidly in their search for newly
emerged females. After mating, each female deposits a
large batch of eggs on the trunk or the underside of a
branch; the eggs are then camouflaged by a spongy
coating that incorporates numerous body hairs. The
eggs hatch in the following April or May. The young
larvae eventually wander away to feed on the bursting
buds and expanding leaves. Larvae develop through six
instars, becoming fully grown in about 2-3 months.
They then pupate on the host plant or elsewhere. Adults
emerge 2-3 weeks later.

834 Male gypsy moth ( Lymantria dispar ).

835

DAMAGE
Larvae cause considerable defoliation, and infestations
are particularly severe on small trees and on those
growing in light, sunny positions.

835 Larva of gypsy moth ( Lymantria dispar ).