Vol 10 Part 14. An introduction to the immature stages of British Flies ...

Larvae of six of the seven subfamilies (Manotinae not yet described) may be
separated as follows (after Madwar 1937).
Larva with one pair of thoracic and 8 pairs of abdominal spiracles (8th pair with horned
prominences in Ditomyia) (figs 79-80) . . . . . . . . . . . . Ditomyiinae
Larva with one pair of thoracic and at most 7 pairs of abdominal spiracles, or without
spiracles (Keroplatinae) . . . . . . . . . . . . 2
2 Antennae well developed, composed of three segments (fig. 81). Bolitophilinae
Antennae rudimentary, composed of one segment . 3
3 Larva free; locomotory pads present (fig. 82) Mycetophilinae
Larva enclosed in slimy tube, or in web; pads absent 4
4 Larva without spiracles, vermiform (worm-shaped) . Keroplatinae
Larva with spiracles, not vermiform . . . . 5
5 Larva peripneustic (fig. I) . . . . . . . . . most Sciophilinae
Larva propneustic (fig. I) . . . . . . . . . . . . . . 6
6 Epicranial plates meeting as usual on ventral surface (fig. 86) . . . . . . .
. . . . . . . . . . . . . . . . (Genus Speolepta) Sciophilinae
Epicranial plates not meeting on ventral surface . . . . Diadocidiinae
The larvae ofMycetophilidae are mostly found in the larger fungi and it is probable
that even when found elsewhere the majority are feeding on microfungi or fungal
hyphae.
Chandler (in Stubbs & Chandler, 1978) lists fungus associations for 130 British
species of Mycetophilidae and Hutson et al. (1980) give considerable information on
life histories. Mad war (1937) and Lastovka ( 1971) describe some immature stages.
There are three recognisable stages in the development of a soft fungal fruiting body
(sporophora): I, fresh with no signs of decay; 2, decaying through age and damage
(mostly by fungivores); 3, semi-liquid, advanced state of decay (some tougher fungi
desiccate rather than rot and are unsuitable for fungus-gnats).
Most mycetophilids attack the first two stages but some species will continue to
develop in the last stage of almost any rotting fungus (e.g. Mycetophilafungorum De
Geer). Other habits and habitats are discussed below under subfamilies.
There is plenty of scope for research on the immature stages provided care is taken
to identify the fungi and the adult flies correctly. Adults of all subfamilies except
Mycetophilinae are keyed in Huston et al. (1980); other taxonomic literature is cited in
that work.
Ditomyiinae. There are only two genera of this subfamily in Britain, each with a
single species. The characteristic larvae of Ditomyia fasciata Meigen (fig. 80) have
been reared from a variety of hard polyporaceous fungi including Coriolus,
Fomes, Daedalea, Polyporus, Bjerkandera, Trametes, lnonotus, Leptoporus. Symmerus
annulatus (Meigen) (fig. 79) is found in rotting logs.
Diadocidiinae. There is only one genus (Diadocidia) of this subfamily in Britain
with three species, two of which are found in rotting wood and associated with the
fungus Peniophora. The larva differs from that of other Mycetophilidae in having the
epicranial plates separated ventrally.
Bolitophilinae. This subfamily has only one genus Bolitophila which is Holarctic in
distribution. The known larvae are gregarious and have all been found in the soft
fruiting bodies of fungi. Bolitophila hybrida (Meigen) is very common in Paxillus
involutus (Batsch. ex Fr.) Fr. and B. saundersi Curtis (fig. 81) is usually found in
Hypholomafasciculare (Huds. ex Fr.) Quelet, but both species occur in other fungi.
Some species appear to be restricted to a few closely related fungi (i.e. are
stenophagous), e.g. Bolitophila cinerea Meigen on Hypholoma and Pholiota spp.
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