Agriculture Reference
In-Depth Information
ORDER COLEOPTERA (BEETLES)
Minute to large insects with biting mouthparts;
forewings modified into horny or leathery elytra
which usually meet in a straight line along the
back; hindwings membranous and folded be-
neath the elytra when in repose, but often re-
duced or absent; prothorax normally large and
mobile. Metamorphosis complete. Eggs usually
spherical, oval, egg-shaped or sausage-shaped.
Larvae usually with a distinct head and with
three pairs of thoracic legs, but sometimes
apodous; often campodeiform or eruciform and,
occasionally, scarabaeiform. The largest insect
order, with over 250000 species worldwide.
EXAMPLES:
Bembidion
spp. (brassy ground
beetles),
Harpalus rufipes
(strawberry seed
beetle),
Pterostichus
spp. (strawberry ground
beetles),
Trechus
spp.,
Zabrus tenebrioides
(cereal ground beetle).
Suborder POLYPHAGA
Adults with the hind coxae attached to the
metasternum but usually movable and, although
extending posteriorly, rarely ever reaching as far
as the hind margin of the first visible abdominal
sternite; antennae extremely variable in appear-
ance. Larvae with indistinct tarsi and just one
tarsal claw.
Suborder ADEPHAGA
A large group of mainly predacious beetles.
Adults with the hind coxae fused rigidly to the
metasternum (i.e. immovable) and extending
posteriorly to the hind margin of the first visible
abdominal sternite; antennae 11-segmented and
usually filiform or moniliform. Larvae usually
with claw-bearing tarsi.
Superfamily
HYDROPHILOIDEA
A
small group of mainly aquatic beetles. Anten-
nae each terminating in a small, pubescent club
(Fig.
58) and typically shorter than the often very
long maxillary palps.
Superfamily CARABOIDEA
1. Family CARABIDAE (ground beetles)
(p. 126
et seq.)
A
large family of fast-moving, mainly nocturnal
beetles with a characteristic body shape
(Fig.
57),
most ground beetles being readily recognized as
such on sight; each elytron usually with nine lon-
gitudinal ridges, separated by distinct furrows or
series of punctures; elytra sometimes fused to
form a rigid body shield; exoskeleton usually
black, but often with a metallic sheen. Larvae
campodeiform, with ten abdominal segments;
tarsi with one or two claws; mandibles pincer-
like and powerful; cerci present on the ninth
abdominal segment. Adults and larvae of most
species are carnivorous, and several are im-
portant predators of crop pests; some species
are phytophagous, several feeding on plant
seeds.
Fig.
57 A ground beetle,
Pterostichus madidus -
family Carabidae (x4).
