Agriculture Reference
In-Depth Information
Fig. 244
Foreleg of fever fly,
Dilophus febrilis.
often hollow out the seed; they also destroy the
roots and lowermost parts of the shoots. On
potato, the larvae burrow into the flesh of the
tubers to form extensive galleries and cavities.
Adults are useful pollinators of fruit trees.
Fig. 243
Tip of the body of bibionid larvae:
(a)
Bibio:
(b)
Dilophus.
BIOLOGY
Adults emerge from April onwards. Large num-
bers of males often congregate on low vegeta-
tion, including the tips of grasses and cereal
plants. The flies frequently visit open flowers
and, in the spring, are of some benefit as
pollinators of fruit trees and other plants. After
mating, females burrow a few centimetres into
the soil, especially in the presence of rotting veg-
etation or organic manure. Each then forms a
small cell in which a cluster of 200-300 eggs is
laid. Eggs hatch about a month later. The larvae
feed gregariously on the subterranean parts of
plants and, in favourable situations, there may be
several thousand individuals per square metre.
Larvae pass through four instars and then pu-
pate; adults appear a few weeks later. There are
usually two or three generations annually, and
adults tend to be most numerous in the spring
and autumn.
often being reported in fields of winter wheat in
the late winter or early spring. Adults are small
(wings 4.5-6.5mm long); both sexes are black-
bodied but the legs of females are ochreous and
those of males reddish with black femora. The
flies occur from March to June and are often
found resting on the leaves of cereal plants and
grasses.
NOTE Morphological differences between larvae of
the various species of
Bibio
are slight and specific
determinations are not always reliable.
Dilophus febrilis
(L.)
Fever fly
This species is a minor pest of various crops,
including cereals (notably spring barley and
maize), potato and sugar beet, and infestations
tend to occur on damp, heavily manured sites;
damage is also reported on grassland and on
various horticultural crops, including hop and
strawberry. The soil-inhabiting larvae feed on
the roots, tubers and stolons, and attacked plants
often collapse and die. On cereals, the larvae
DESCRIPTION
Adult
mainly shiny black;
pronotum
with two
transverse rows of backwardly directed spines;
wings
4-7 mm long;
fore tibiae
each with an
apical circlet of seven to nine stout spines
(Fig.
244). Egg
0.55 mm long, sausage-shaped, white
