Agriculture Reference
In-Depth Information
BIOLOGY
Adult beetles appear from late April or early
May onwards. They feed on the leaves of mint
plants, usually devouring the edges. The beetles
often rest in the leaf axils during the daytime but
drop to the ground and feign death when dis-
turbed. Eggs are deposited in raft-like groups,
mainly in June and July; they hatch 1-2 weeks
later. Although the larvae are not gregarious,
and individuals disperse soon after egg hatch,
several commonly occur on the same host plant.
The larvae feed mainly at night and become fully
fed in about 4 weeks; there are four larval instars.
Larvae then enter the soil but do not pupate until
the following spring.
Fig. 215
Hindleg of wheat flea beetle,
Crepidodera
ferruginea.
Carduus, Cirsium,
wild grasses and various other
weeds, to feed in the coleoptiles and shoots of
seedlings and in the basal tissue of older plants.
They vacate those that rot or die and readily
transfer to adjacent hosts. The larvae pass the
winter in the soil and re-invade host plants early
in the spring, to become fully grown in May.
They then pupate in the soil and adults emerge
about a month later.
DESCRIPTION
Adult
8-12 mm long, hemispherical, brilliant
metallic green, often tinged with gold or
coppery-bronze, and finely punctured.
Egg
2.0
x 0.8 mm, creamish-white.
Larva
up to 10 mm
long, shiny purplish-black to black;
abdomen
broad, fleshy and distinctly humped.
Pupa
8.0-
8.5 mm long, deep yellow.
DESCRIPTION
Adult
3-4mm long, mainly reddish-brown to
yellowish-red;
elytra
with relatively large and
regularly spaced punctures;
antennae
11-
segmented;
legs
yellow, the first tarsal segment
noticeably swollen
(Fig. 215). Egg
0.75 x
0.45 mm, oval, yellow, darkening soon after be-
ing laid.
Larva
up to 5 mm long;
body
creamish-
white and with a distinct anal pseudopod;
pinacula and dorsal plates
pale brown;
head
brown marked with black;
thoracic legs
small and
partly black;
anal plate
brownish-black.
Crepidodera ferruginea
(Scopoli)
Wheat flea beetle
Larvae of this flea beetle are associated with
grasses and various weeds, and are often
common in established leys. If infested pasture
is ploughed-up and subsequently drilled with
wheat or other cereal crop, the larvae may trans-
fer to the new hosts. The larvae bore into the
central shoots, each leaving a minute entry hole
in the base; infested shoots eventually turn
yellow
(Plate
3e). Symptoms are usually most
evident in spring and are superficially similar to
those caused by shoot-mining dipterous larvae,
such as wheat bulb fly,
Delia coarctata,
p. 197
(q.v.).
Crioceris asparagi
(L.)
Asparagus beetle
This beetle is a generally common and important
pest of vegetable asparagus; infestations also
occur on ornamental asparagus and on
Aspara-
gus officinalis.
Adults and larvae feed vora-
ciously on the foliage; they also strip sections
from the bark of the stems and branches, and
BIOLOGY
Adults occur from June to mid-September, and
eggs are deposited in the soil at the base of
various plants from August onwards. The eggs
hatch within 3-4 weeks. The larvae then invade
