442 
THE STUDY OF INSECTS. 
dack Mountains. The larvae live under the bark of decaying 
branches, under fallen leaves, and in sap flowing from 
wounded trees. 
Family Mycetophilid^E (My-cet-o-phil'i-das). 
The Fungus-gnats . 
These flies are of medium or small size, and more or less 
mosquito-like in form. They are most 
easily recognized by the great length 
of the coxae (Fig. 518, c ), and the 
fact that all the tibiae are furnished 
with spurs. They also differ from 
the closely-allied families in lacking, 
as a rule, whorls of hairs on the an¬ 
tennae of the males (Fig. 519), and 
in possessing ocelli. 
At first sight considerable varia¬ 
tion seems to exist in the venation 
of the wings as shown in the three wings represented in 
Figure 520 ; but in reality the variations are comparatively 
slight. Vein I extends along the margin of the wing to the 
end of vein III 4+6 . Vein II varies in length. Vein III pre¬ 
serves three branches in the more generalized form (Fig. 
520,#); in some genera veins III, and III a+3 coalesce from 
the apex of the wing backward for a greater or less distance 
so that the base of vein III 3+3 appears like a cross vein (Fig. 
520, b)\ this coalescence may be complete,in which case vein 
III is only two-branched (Fig. 520, c). Vein V is also 
two-branched. It should be observed that the cross-vein 
III-V extends more or less obliquely or even lengthwise of 
the wing; while the base of vein III 4+6 may extend trans¬ 
versely, and then is liable to be mistaken for a cross-vein 
(Fig. 520, b , c). 
The flies are often found in great numbers on fungi and 
in damp places where there is decaying vegetable matter. 
They are active, and leap as well as fly. 
Fig. 518. Fig. 519. 
