Biology Reference
In-Depth Information
Family CHIRONOMIDAE (non-biting
midges)
Family SCIARIDAE (fungus gnats or sciarid
flies) ( 368 )
Delicate, gnat-like flies with poorly developed
mouthparts, reduced wing venation and no ocelli; male
antennae are plumose.
Small, delicate, gnat-like flies with a characteristic wing
venation, 16-segmented antennae, large compound eyes
(which usually meet above the antennae to form an 'eye
bridge') and a somewhat humped thorax. The larvae are
elongate and translucent-whitish, with a conspicuous
black head.
Bryophaenocladius furcatus (Kieffer)
A widely distributed, parthenogenetic midge, the larvae
sometimes damaging the roots of greenhouse plants,
including ornamentals such as primrose ( Primula
vulgaris ) and Rhododendron . Infestations are most
likely to develop in damp conditions. Fully grown
larvae are 5 mm long, and yellowish green with a dark
brown head; the anal segment bears prominent ventral
tubercles (cf. family Sciaridae).
Bradysia spp.
Various species of sciarid fly, including Bradysia aprica ,
B. difformis (syn. B. paupera ), B. ocellaris (syn. B.
tritici ) and B. tilocola (syn. B. amoena ), are associated
with ornamental plants. The larvae sometimes damage
cuttings, seedlings and young pot plants by tunnelling
into the roots, corms or main stems. However, such
attacks are usually limited to plant material already
invaded by moulds or other micro-organisms. The
growth of attacked cuttings and seedlings is checked;
plants may also collapse and die. Adult sciarids are
very active, and are often seen flitting or scurrying
about the base of cuttings, seedlings or older plants. The
egg-laying females are much attracted by dried-blood
fertilizer and steam-sterilized soil, each depositing
100 or more eggs in the growing medium close to host
plants. The eggs are small ( c. 0.2
0.1 mm), oval and
translucent-whitish; they hatch several days later, the
incubation time varying considerably according to
temperature. The larvae feed for 3-4 weeks, usually
attacking the root hairs; they then construct silken
cocoons within which to pupate, adults emerging about a
week later. More rarely, eggs are placed directly onto
plants; the larvae then feed on the leaf tissue and may
eventually pupate on the foliage. Breeding is continuous
under suitable conditions.
×
368
368 Larva of a sciarid fly (family Sciaridae).
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