Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 336

900

LIFE HISTORY
Adults occur in June and July. Eggs are laid on the
foliage of various plants, and hatch in 10-14 days.
Young larvae then feed gregariously from late July or
August onwards. The larvae hibernate throughout the
winter, reappearing in the following spring. They then
feed singly, becoming fully grown in May. Pupation
takes place in the soil in flimsy cocoons.

DAMAGE
Larvae cause defoliation which, if extensive, may be
of importance, particularly on greenhouse-grown
chrysanthemums; flowers are also destroyed. 900 Large yellow underwing moth ( Noctua pronuba ).

Noctua pronuba (Linnaeus) ( 900-902 )
syn. Triphaena pronuba (Linnaeus)
Large yellow underwing moth
A generally common pest of low-growing plants,
including herbaceous ornamentals such as Anemone ,
Chrysanthemum , Dahlia , Dianthus , pot marigold
( Calendula officinalis ) and primrose ( Primula
vulgaris ); seedling trees and shrubs in nurseries are also
attacked. Although mainly an outdoor pest, infestations
also occur on greenhouse-grown plants. Palaearctic.
Present throughout Europe.

901

DESCRIPTION
Adult: 50-60 mm wingspan; fore wings yellowish
brown, greyish brown to dark rusty brown; hind wings
yellow, with a blackish-brown border. Egg:
hemispherical, creamy white to purplish grey. Larva:
up to 50 mm long; greyish brown, dull yellowish or
greenish, with three pale lines along the back, the outer
pair bordered inwardly with short blackish bars on each
abdominal segment; spiracles white with black rims;
head relatively small, light brown, marked with black.
Pupa: 22 mm long; plump and reddish brown;
cremaster with two strong, divergent spines.

901 Egg batches of large yellow underwing moth ( Noctua
pronuba ) on leaves of Iris .

902

LIFE HISTORY
Adults occur from mid-June to August. Although active
mainly at night, the moths are readily disturbed during
the daytime; they then career wildly through the air
before resettling, the flash of colour displayed by the
hind wings making them particularly obvious. Eggs are
laid in large, neat batches, often on the leaves of
monocotyledonous plants such as Gladiolus and Iris .
They hatch in 2-3 weeks, earlier or later depending on
temperature. Larvae occur from July onwards. They
feed both above ground on leaves and flowers, and in
the soil on roots and crowns. A few individuals feed up
rapidly to produce a partial second generation of adults

902 Larva of large yellow underwing moth ( Noctua pronuba ).

in the autumn; however, most do not complete their
development until the following May. Pupation takes
place in a subterranean, earthen cell but without forming
a cocoon. Unlike Agrotis segetum (pp. 333-4), larvae of
this species are little affected by weather conditions and
frequently cause damage to crops in cool, wet seasons.