Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 215

508

Family GRACILLARIIDAE

Very small moths with narrow wings fringed by long
cilia; adults adopt a typical resting posture, with the
head end raised up by the long, widely splayed front
legs. The larvae are 14-legged (prolegs absent on the
sixth abdominal segment); they are mainly leaf miners
and, in their young stages, are apodous and have a
peculiar flattened head. The pupa typically protrudes
from the cocoon following emergence of the adult.

Acrocercops brongniardella (Fabricius)
( 508-510 )
An often abundant pest of oak ( Quercus ), including
holm oak ( Q. ilex ). Widely distributed in mainland
Europe; very local in the British Isles, and found mainly
in the southern half of England, south-east Wales and
southern Ireland. Also present in Asia and North Africa.

508 Adult of Acrocercops brongniardella .

509

DESCRIPTION
Adult: 8-10 mm wingspan; fore wings ochreous brown
to brown, marked with white; hind wings grey. Larva:
up to 7 mm long; translucent, pale yellowish brown,
with a blackish gut; pinacula and a series of oval dorsal
plates, shiny greyish brown; head and prothoracic plates
pale yellowish brown.

LIFE HISTORY
Eggs are laid in the spring on the upper side of oak
leaves. Larvae then mine the leaves, several individuals
commonly feeding in the same leaf. The mines
commence as silvery galleries and, later, develop into
blotches; these eventually join to form an expansive
mine that becomes distinctly bloated and may occupy
most of the leaf. The blotches often become partly filled
with moisture but this does not appear to harm the
occupants. Larvae are fully fed by late June or early
July. They then pupate in cocoons formed amongst
debris on the ground. Adults appear in late July or early
August and then overwinter; they reappear in April and
May. There is usually just one generation annually but,
in favourable situations, there may be at least a partial
second.

509 Larva of Acrocercops brongniardella .

510

DAMAGE
The larval mines disfigure host plants, and are most
obvious and important on hedges of holm oak.

510 Mine of Acrocercops brongniardella in leaf of Quercus ilex .