Agriculture Reference
In-Depth Information
Main Insect Orders
ORDER HEMIPTERA (TRUE BUGS)
Family PIESMATIDAE
Piesma quadratum
(Fieber)
Beet leaf bug
the antennae (see Fig. 22);
eyes
red and promi-
nent;
pronotum
with three longitudinal ridges
anteriorly (cf.
Piesma maculatum,
below).
Egg
elongate-oval, yellowish-brown.
Nymph
yel-
low when freshly emerged, gradually becoming
greener or browner.
This locally distributed species is a potentially
important pest of sugar beet in parts of continen-
tal Europe where, in addition to causing a pale
mottling of infested foliage, it is also a vector
of beet leaf crinkle virus (a disease not found in
the British Isles). In the British Isles, this insect
is associated mainly with wild Chenopodiaceae,
e.g.
Atrlplex littoralis, Beta vulgaris
and
Halimione portulacoides,
growing along the
coast of East Anglia.
Piesma maculatum
(Laporte de Castelnau)
Spinach beet bug
This bug is distinguished from the previous
species by the presence of just two longitudinal
ridges on the pronotum; adults are also slightly
smaller (up to 2.8mm long). Eggs are laid in the
spring on both sides of expanded leaves and
also on the petioles. The nymphs develop rap-
idly, producing pale feeding marks on infested
tissue and causing noticeable leaf curling. There
is one main generation each year but, in favour-
able areas, at least a partial second. Although
associated with beet crops in various parts of
Europe, including East Anglia and other parts
of the British Isles, this species is not a vector of
beet leaf crinkle virus.
BIOLOGY
Adults overwinter in sheltered field margins,
hedgerows and other similar situations. They re-
appear in the spring and then migrate to host
plants where, eventually, eggs are laid. The eggs
hatch about 2 weeks later. Nymphs then feed on
the leaves for about 6 weeks before moulting
into adults, usually from July onwards. In favour-
able situations there may be at least a partial
second generation.
Family MIRIDAE (capsid bugs)
Calocoris norvegicus
(Gmelin)
Potato capsid
DESCRIPTION
Adult
2.5-3.5 mm long, grey to brownish or
greenish;
body
flattened and with distinctive
lace-like punctures dorsally;
jorewings
with a
lace-like, punctate pattern (see Fig. 23);
head
with a pair of horn-like projections between
Infestations of this widely distributed and often
abundant capsid occur on various herbaceous
plants, including chrysanthemum, and on field
