Agriculture Reference
In-Depth Information
silken cocoons within which to pupate, and
adults emerge about a week later. More rarely,
eggs may be placed directly onto plant tissue; the
larvae then feed on the leaf tissue and may even-
tually pupate on the foliage. Under suitable con-
ditions breeding is continuous.
DESCRIPTION
Adult
3.0-3.5 mm long, black, with a greyish-
brown abdomen;
eye bridge
present (see Fig.
87) (cf. cucumber sciarid fly,
Pnyxia scabiei,
p. 168);
legs
yellowish;
antennae
relatively short
and thick;
palps
3-segmented (cf. cucumber
sciarid fly,
P. scabiei,
p. 168).
Egg
0.2 x 0.1 mm,
oval, translucent-whitish.
Larva
up to 6 mm
long, elongate, translucent-whitish;
head
shiny
black.
Fig. 245
Larva of fever fly,
Dilophus febrilis
(x6).
when newly laid, becoming slightly darker at
each end.
Larva
up to 12mm long, dull, light
brown, more or less cylindrical; each body seg-
ment with several relatively short papillae
(Fig. 245)
(cf.
Bibio,
Fig. 85);
head
prominent,
blackish-brown (cf. leatherjackets, e.g.
Tipula
spp., p. 164);
posterior spiracles
each with three
pores
(Fig. 243b). Pupa
7.5 mm long, whitish,
darkening to brownish-grey;
head
with one (fe-
male) or three (male) pointed anterior processes
(cf.
Bibio,
p. 165).
Bradysia amoena
(Winnertz)
This relatively small, dark-bodied species occurs
commonly in association with pot plants. The
adults are similar to those of
Bradysia paupera
(above) but have longer, thinner antennae; they
are active at virtually any time of year and fre-
quently attract attention in dwelling houses; the
larvae can cause injury to seedlings and small
plants but are rarely important.
Family SCIARIDAE (sciarid flies)
Bradysia paupera
Toumikoski
This sciarid is a common and often important
pest that can check the growth of glasshouse
cuttings, seedlings and young pot plants, in-
cluding cucumber, lettuce, melon and various
ornamentals. Attacked plants may also wilt and
die, especially in sunshine. Less frequently,
when eggs are deposited on leaves, the larvae
skeletonize the foliage.
Bradysia aprica
(Winnertz)
Infestations of this small, widely distributed
sciarid often occur in glasshouses, where the lar-
vae cause minor damage to pot plants. Adults
are dark-bodied with pale halteres, pale legs and
clear wings.
BIOLOGY
Adult sciarids are very active, and are often seen
flitting or scurrying about at the base of cuttings,
seedlings or older plants. The egg-laying females
are much attracted to dried blood fertilizer and
to steam-sterilized soil; each will deposit 100 or
more eggs in the soil close to host plants. Eggs
hatch several days later, the incubation time
varying considerably according to temperature.
The larvae feed for 3-4 weeks and usually attack
the root hairs; when fully fed, they construct
Bradysia brunnipes
(Meigen)
This species is often common in mushroom
houses, and the adults are sometimes a nuisance
to pickers. The larvae feed in the casing. Al-
though implicated in the spread of diseases,
they do not damage the mushrooms directly (cf.
mushroom sciard fly,
Lycoriella auripila,
p. 168).
Adults are blackish (females have a paler abdo-
men), with slightly smoky wings (wing length:
3.0-4.5 mm) and yellow halteres.
