590 
DIPTERA. 
are found about flowers and leaves, and the larvae are many of them 
scavengers. The flies are generally lazy and not easily frightened, and 
are fond of sitting on leaves near the 
ground in damp rather shady places. PL 
LXI, fig. 3, shows the commonest species 
of the plains (Sargus metallinus) and give 
some idea of the beautiful colouring which 
these flies often show. The wings are 
carried at rest lying flat over each other 
along the abdomen and the members of 
the family have generally a characteristic 
look about them which makes them easy 
to recognise; where there is a doubt, a 
glance at the antennae and venation will 
in most cases be enough to resolve it. 
The sexes may be distinguished by the 
distance apart of the eyes. The larvae, 
which are sometimes predaceous, are found 
in various decaying substances, under bark 
or in the sap exuding from it, and often in 
water, even occasionally in salt water 
and hot springs. The aquatic forms often 
possess a beautiful hair-fringed tail-cup 
(fig. 379) which floats and keeps the 
posterior spiracles at the surface. The 
skin of the larva is often very strong and 
hard, frequently covered with a sort of 
chalky layer which helps to stiffen it, 
and when the larva pupates this larva- 
skin separates from the pupa but remains 
enclosing it as a protecting outer case. 
Interesting accounts of the structure and 
habits of these larvse will be found in 
Miall (“ Aquatic Insects ”). 
The student will find a list of genera 
and species in Indian Museum Records 
(Brunetti). 
Fig. 3 SI—Larval skis - of a stra- 
TIOMYIID TO SHOW TAILFRINGE. 
UPPER FIG. X 2. 
Fig. 382 -Larva of a stratio- 
MYIII), VENTRAL VIEW. 
