Agriculture Reference
In-Depth Information
tions lead to the development of large patches or
extensive areas of dead plants. Attacks are en-
couraged by continuous cereal growing or by
cereal/grass rotations, and by the presence in
fields of grass weeds and cereal volunteers; also,
attacks are most likely to occur in years when the
weather from late summer into early autumn re-
mains warm and dry.
BIOLOGY
Adults occur from late June or early July on-
wards. They are active at night and feed on the
leaves and other parts of cereals and grasses.
Eggs are laid in the soil from mid-August on-
wards. They are either deposited singly or in
small groups, 20 cm or more below the surface,
and hatch in about 2 weeks. Each larva inhabits
an earthen burrow which extends for a consider-
able depth and into which (at night) portions of
leaves are dragged, to be consumed during the
daytime. The larvae feed throughout the autumn
and winter, and they remain active except in cold
weather; cool, wet conditions are unfavourable
for their survival. They pass through three instars
and complete their development in the following
May. Pupation occurs in the soil and adults
emerge 2-3 weeks later.
Fig. 199
Strawberry seed beetle,
Harpalus rufipes
(x4).
adults emerge, and eggs are eventually laid in the
soil a few centimetres below the surface. The
eggs hatch shortly afterwards and larvae feed
into the autumn before hibernating. A propor-
tion of the adult population also overwinters.
DESCRIPTION
Adult
14-18 mm long, mainly black with partly
reddish legs and reddish-brown antennae;
pronotum
heavily punctured posteriorly;
wings
fully developed
(Plate 3b). Larva
up to 30 mm
long;
body
greyish-white to creamish-white, with
brown dorsal plates and small lateral plates on
each abdominal segment;
head
brownish-black;
mandibles
large and powerful;
thorax
mainly
brown;
thoracic legs
well developed;
ninth ab-
dominal segment
terminating in a pair of spinose
cerci
(Plate 3c).
DESCRIPTION
Adult
11-17 mm long, dull black with a yellowish
pubescence on the elytra
(Fig. 199);
legs and an-
tennae
reddish.
Zabrus tenebrioides
(Goeze)
Cereal ground beetle
In mainland Europe, this carabid is an important
pest of barley, maize, rye and wheat; it is also
associated with grasses, especially
Poa pratensis.
In recent years, locally important outbreaks have
occurred in cereal crops in several parts of south-
ern England, usually on medium-textured calcar-
eous soils. Damage is characteristic, the larvae
causing extensive shredding of leaves and shoots
(Plate 3a),
and also dragging plant tissue down
into their subterranean burrows; heavy infesta-
Family HYDROPHILIDAE
(mud beetles)
Helophorus nubilus
F.
Wheat shoot beetle
The wheat shoot beetle is an occasional and
minor pest of wheat and, occasionally, oats;
