Agriculture Reference
In-Depth Information
stripes on the thorax;
antennae
14-segmented;
wings
up to 23 mm long, shorter than the abdo-
men (cf.
Tipula oleracea,
below);
legs
very long,
narrow and fragile.
Egg
1.1 x 0.4 mm, elongate-
oval, shiny black
(Fig. 241b). Larva
up to
45 mm long, dull brownish-grey, plump with a
soft but tough skin;
head
black but indistinct;
posterior papillae
fleshy and often tapered - the
dorsal and lateral pair on the spiracular disc
elongated and of similar length, the dorsal pair
of anal papillae elongate and the ventral pair
rounded
(Fig. 242b)
(cf. spotted crane fly,
Nephrotoma appendiculata,
p. 163).
Although the larvae can be harmful, adult bib-
ionids are often useful pollinators of fruit trees.
BIOLOGY
Adults are active from April to June, and the
males typically hover in large swarms over the
ground, hedges and other vegetation. Egg-laying
females are attracted to decaying vegetable mat-
ter, where they then dig down into the soil for a
few centimetres before depositing eggs in raft-
like groups. Eggs hatch about 5 weeks later. The
larvae, which feed gregariously, develop rela-
tively slowly and do not reach the pupal stage
until the late winter or early spring.
DESCRIPTION
Adult
black-bodied, very hairy (especially male)
and relatively large;
wings
8-12 mm long.
Egg
0.75 mm long, sausage-shaped, white when
newly laid but soon becoming darker at each
end.
Larva
up to 24mm long, dull greyish-
brown, with distinctive fleshy papillae on the
body - these, in common with other species of
Bibio
(see Fig. 85), are longer, more slender and
more numerous than in the genus
Dilophus
(p.
166);
head
dark brown;
spiracles
on last body
segment each with just two pores (typical of
Bibio)
(Fig. 243a)
(cf.
Dilophus
p. 166).
Pupa
12-14 mm long, the abdominal segments orna-
mented with several small spines;
head
with just
one anterior process, that in the female being
relatively small (typical of
Bibio;
cf. Dilophus,
p. 166).
Tipula oleracea
L.
A common crane fly
Adults of this generally common species appear
earlier in the year than those of
Tipula paludosa
(above). Larvae also occur somewhat earlier and,
as a result, often cause noticeable damage to
plants in the same year as eggs were laid. Unlike
those of the previous species, gravid females are
usually able to fly away from emergence sites, so
there is less likelihood of populations in following
crops escalating to damaging levels. It has been
observed, however, that emerging adults can be
'trapped' beneath the canopy of post-flowering
oilseed rape crops; this can result in the appear-
ance of unusually large populations of larvae of
this species in following winter wheat crops. Un-
like
T. paludosa,
this species has two generations
per year, adults occurring at various times from
April to October. The antennae of adults are
13-segmented and the wings (wing length: 18-
28mm) are at least as long as the body (cf.
T.
paludosa,
above); larvae are distinguishable from
those of
T. paludosa
by the two pairs of elongated,
subtriangular anal papillae.
Bibio hortulanus
(L.)
March fly
This is a relatively small species (wings 5.5-
9.5mm long); males are black-bodied but fe-
males have the abdomen and part of the thorax
orange-red; the legs are entirely black in both
sexes (cf.
Bibio johannis,
below). Adults occur in
May and June. The larvae occasionally cause
damage in the late winter or early spring, par-
ticularly to crops of winter wheat.
Family BIBIONIDAE (St. Mark's flies)
Bibio marci
(L.)
St. Mark's fly
This generally abundant fly is a minor pest of
cereals and grasses. The larvae graze on the roots
and sometimes cause plants to wilt and die. Infes-
tations typically occur in heavily manured sites.
Bibio johannis
(L.)
Larvae of this species are sometimes damaging
to cereals and other crops, infestations most
