Agriculture Reference
In-Depth Information
Fig. 248
Puparium of hessian fly,
Mayetiola
destructor
(x!5).
BIOLOGY
Adults of the first generation appear in March
or April. Eggs are deposited in batches on the
leaves of host plants, and they hatch about a
week later. The larvae feed within the shelter of
leaf sheaths at the base of the plant and complete
their development in approximately 3 weeks.
They then pupate
in situ
to form a cluster of
seed-like puparia (this is the so-called 'flax-seed'
stage)
(Plate 6d).
Adult midges appear about 3
weeks later, but development times vary consid-
erably according to temperature. There is usu-
ally at least one further generation, or partial
generation; puparia form the overwintering
stage.
Fig. 247
Hessian fly,
Mayetiola destructor
(xl5).
tip of the abdomen;
wings
0.8 mm long.
Paedogenetic larva
up to 3 mm long, white,
tapered anteriorly, but somewhat rounded
posteriorly, with a pair of anterior eye-spots
meeting to form an 'X'.
'Imago' larva
similar in
appearance to paedogenetic larva but with a
sternal spatula and separated eye-spots.
Mayetiola destructor
(Say)
Hessian fly
DESCRIPTION
Adult
black with a brownish or brownish-red
abdomen
(Fig. 247). Egg
0.5 mm long, sausage-
shaped, red.
Larva
up to 4 mm long, whitish,
translucent;
sternal spatula
robust, with a bifid
tip.
Puparium
4 mm long, dark brown, resem-
bling a seed of flax
(Fig. 248).
The hessian fly is associated mainly with wheat
but will attack barley and rye;
Elytrigia repens
is also a host. The larvae produce a noticeable
swelling at the base of young plants; later, they
also cause the leaf nodes to swell. The ears of
infested plants may turn whitish and the grains
often shrivel; infested plants may also lodge or
break off in the wind, and this contributes to
further yield loss. Although of relatively little
importance in the British Isles, hessian fly is a
major pest in many other wheat-growing coun-
tries, particularly North America.
Mayetiola avenae
(Marchal)
Oat stem midge
This species is similar in habits and appearance
to
Mayetiola destructor
(above) but is associated