Biology Reference
In-Depth Information
693
694
693
Larval habitation of pine resin-gall moth (
Petrova
resinella
) on
Pinus
.
694
Female Leche's twist moth (
Ptycholoma lecheana
).
695
Petrova resinella
(Linnaeus) (
693
)
Pine resin-gall moth
A minor and locally common pest of pine (
Pinus
), the
characteristic larval habitations occasionally attracting
attention on young amenity trees. Adults occur in June,
eventually depositing eggs on the young shoots. After
egg hatch each larva bores into the base of a needle and
also damages the surface of the stem, forming a groove
from which resin exudes; the larva then feeds close to a
bud whorl, protected by silk and a coating of resin
which, at this stage, forms a pea-like gall. Feeding
continues throughout the following year, the protective
gall becoming greatly enlarged (
c.
20-30 mm across)
and obvious. Pupation occurs in the following spring,
almost two years after eggs were laid. Adults
(16-22 mm wingspan) have whitish fore wings, mottled
with grey and blackish brown; the hind wings are
brown, with white cilia.
695
Larva of Leche's twist moth (
Ptycholoma lecheana
).
another along each side; pale yellowish green below;
pinacula yellowish; head yellowish brown to black;
prothoracic plate pale yellow to yellowish brown,
marked on sides with black; anal comb small; thoracic
legs black.
Pupa:
9-11 mm long; black; apical hook-
like setae on cremaster forming a strong projection.
Ptycholoma lecheana
(Linnaeus) (
694-695
)
Leche's twist moth
A generally common, polyphagous species but
associated mainly with oak woodlands; a minor pest of
trees and shrubs including crab-apple (
Malus
),
hawthorn (
Crataegus
), hazel (
Corylus
), oak (
Quercus
),
poplar (
Populus
), sycamore (
Acer pseudoplatanus
) and
willow (
Salix
); conifers such as fir (
Abies
), larch (
Larix
)
and spruce (
Picea
) are also attacked. Eurasiatic. Widely
distributed in Europe.
LIFE HISTORY
Adults occur in June and July. Eggs are deposited on
various host plants and hatch in the summer. Young
larvae then feed on the foliage for a few weeks and then
hibernate, each in a silken cocoon spun on a twig or spur.
The larvae reappear early in the following spring, to feed
on the opening buds and young foliage. Later they feed
in rolled leaves, and become fully grown in May or early
June. Pupation occurs in a dense, white cocoon formed
in the larval habitation or in a freshly rolled leaf.
DESCRIPTION
Adult:
16-22 mm wingspan; fore wings blackish
brown, suffused with greenish yellow, particularly
basally, and with silver-metallic markings; hind wings
blackish brown, with pale cilia.
Egg:
1.0
0.7 mm,
oval, flat and light green.
Larva:
up to 20 mm long;
bluish green, with a darker line along the back and
×
DAMAGE
Larvae cause defoliation and damage to young shoots but
are rarely sufficiently numerous to be a major problem.
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