Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 299

780 781

780 Female northern winter moth ( Operophtera fagata ). 781 Larva of northern winter moth ( Operophtera fagata ).

pale yellowish green when newly laid but soon
becoming orange-red. Larva: up to 25 mm long; rather
plump, light green, with a dark green dorsal stripe and
several whitish or creamy-yellow stripes along the back
and sides, including a pale yellow line passing through
the spiracles (cf. Alsophila aescularia , p. 297). Pupa:
7-8 mm long; brown and stumpy; cremaster with a pair
of laterally directed spines.

DAMAGE
Larvae cause considerable defoliation, and often
completely strip the leaves from the branches of heavily
infested host plants. Attacks on the buds and blossoms
are also of importance; complete trusses may be
destroyed.

Operophtera fagata (Scharfenberg) ( 780-781 )
syn. Cheimatobia boreata (Hübner)
Northern winter moth
Adults of this widely distributed species occur in
October and November. They are similar in appearance
and habits to those of Operophtera brumata , but the
females have slightly longer wings and the males are
lighter in colour. Larvae (up to 21 mm long) are mainly
green, with greyish-white lines along the back and
sides, black spiracles and a black head. They feed on the
foliage of host plants in May and June and, if numerous,
cause noticeable defoliation. Attacks are most
frequently established on beech ( Fagus sylvatica ) and
birch ( Betula ) but also develop on other trees and
shrubs; minor infestations are sometimes noted on
ornamentals and nursery stock.

LIFE HISTORY
Adults occur from October to January but are most
abundant in November and December. The males are
active at night and are strongly attracted to light. They
often rest openly on walls and fences during the daytime
but the spider-like females hide on tree trunks and are
less often seen. Mating takes place at night, copulating
pairs occurring on the trees with the males
characteristically standing head downwards, with the
wings held outwards like a settled butterfly. Eggs, about
100-200 per female, are deposited singly in crevices in
the bark. They hatch in late March or April and the
newly emerged larvae then attack the buds, blossoms
and expanding leaves. At this stage, the minute larvae
are also blown about in the wind, each on a silken
thread; they are then often carried into previously
uninfested nurseries and gardens from adjacent
woodland trees and hedges. Feeding continues until late
May or early June, the rather sluggish larvae spinning
two leaves loosely together with silk, or feeding within
the blossom trusses, sheltered by the overlying petals or
calyxes. Fully grown larvae drop to the ground and
enter the soil to pupate in flimsy cocoons about 8-10 cm
below the surface.