Agriculture Reference
In-Depth Information
from August or September onwards and, if nu-
merous, can cause severe damage, with grass
often dying out in patches. Larvae are up to
22 mm long, whitish and translucent, with numer-
ous gingery body hairs and spines; the head is
pale yellowish-brown with powerful, matt-black
mandibles; also, the body is strongly flexed, with
the head held tightly against the anal segment;
the spines on the anal segment are arranged ir-
regularly
(Fig. 203b).
Adults are 7-11 mm long
and black, with reddish-brown elytra and reddish
legs.
ited deeply in the soil, usually at a depth of 60 cm
or more, typically in batches of 12-30. They
hatch in about 6 weeks. Larvae then feed on the
subterranean parts of plants for up to 3 years
before becoming fully grown, passing through
three instars. They then pupate, usually in their
third summer, each in an earthen cell. The adult
stage is reached about 6 weeks later, but indi-
viduals remain in the pupal cell and do not
emerge from the soil until the following spring.
Mass emergence of adults often occurs at regular
intervals, e.g. every 3 years, coinciding with the
main local developmental phase of the larvae.
Melolontha melolontha
(L.)
Cockchafer
DESCRIPTION
Adult
20-30 mm long, pale chestnut-brown with
a darker head and pronotum;
elytra
partly
clothed in whitish hairs;
abdomen
protruding
beyond the elytra and terminating in a blunt
spine;
antennae
with six (in female) or seven (in
male) lamellae.
Egg
3 x 2 mm when newly laid,
yellowish or whitish.
Larva
up to 50 mm long;
body
mainly white and sac-like;
head
brown;
anal
segment
translucent, the anal slit wavy, trans-
verse and surmounted by two longitudinal, par-
allel rows of spines
(Fig. 203c).
Larvae of this large chafer occur mainly in grass-
land, although the adults tend to be most numer-
ous in association with forests, woods and
hegderows. The larvae are capable of causing
considerable damage, as they bite through the
roots and burrow into other subterranean parts
of plants. Cereals, hop, lettuce, potato, straw-
berry and sugar beet are particularly vulnerable,
especially when such crops are planted in re-
cently ploughed-up pasture. Adult cockchafers
graze on the foliage and flowers of shrubs and
trees and are considered important forestry
pests. The adults also attack developing fruitlets
of fruit trees, removing parts of the flesh; bites
sometimes reach down to the core. Chafer-
damaged fruits either fall prematurely or remain
on the tree; in the latter case, the injured tissue
heals over and, depending upon the degree of
injury, develops into corky patches or pits. Simi-
lar fruitlet damage is caused by caterpillars of
pests such as clouded drab moth,
Orthosia
incerta
(p. 243), and winter moth,
Operophtera
brumata
(p. 231).
Phyllopertha horticola
(L.)
Garden chafer
Infestations of this often abundant chafer are
most frequent in grassland, including golf
courses and other amenity areas. The larvae de-
stroy the root system of the turf, and this results
in the appearance of large, dead patches. The
loosened turf is often removed by birds, such as
rooks, that commonly search infested areas for
the grubs. Fine-leaved grasses are most suscep-
tible to chafer attack; broader-leaved species,
including cocksfoot and rye-grass, are more tol-
erant. Damage is especially severe on lighter
soils and is also of particular significance on wet,
upland pastures. Although primarily pests of
grass, the larvae will also damage crops planted
in recently ploughed-up grassland. The adult
chafers sometimes browse on the leaves and
developing apple and pear fruitlets, and may also
cause minor damage to various other plants.
BIOLOGY
Adult cockchafers are active at night in May and
early June, and are often attracted to lighted
windows. They feed on the foliage of various
shrubs and trees. They often roost in trees and
bushes during the daytime and remain in a coma-
tose state even when disturbed. Eggs are depos-
