ON INDIAN PARASITIC FLIES. 377 
the larval stage which to the parasitologist is the interesting stage. 
The eggs are laid by the flies on the stems of plants and when the 
young larvae emerge they must reach a spider. It is perhaps for 
this purpose, that they are endowed with unusual leaping powers. 
They are amphineustic, short, thick, 12-segmented with small head 
and smaller mouth parts. They burrow into the abdomen of the 
spider and feed on the tissues. When full fed the larva eats a way | 
out and the dried skins of the spiders are found with a circular orifice 
clearly showing what has happened. The larva then pupates and 
the pupa lies in the spider’s web until the fly emerges. Not having 
to dig itself free like the members of the previous family, the Cyrtid 
pupa has no cephalic spines but on the dorsum of the thorax there 
is a longitudinal row of spines the use of which is unknown. 
One matter in connection with the respiration of the parasitic 
larva deserves to be mentioned. The hind spiracles are surrounded 
by large and peculiar plates. Respiration is a matter which must 
always present a problem for the internal parasite. In one case the 
Cyrtid larva has been found lying in the abdomen of the host (a 
spider of the genus Cteniza) with the terminal spiracles actually in 
the lungs of the spider from which it, doubtless, obtained its oxygen. * 
When the flies es.1gc liom the pupa they frequent flowers and 
grass. They have rather small wings and no great powers of flight. 
The halteres are quite concealed by large horizontal squamae which 
have been previously referred to. 
Phoride. This is an interesting family of small black and yellow 
flies with varied and remarkable habits. They have been collected 
from most parts of the world and are common in India, more so per- 
haps in the hills than in the plains. They have a hunch-backed 
appearance, well developed legs and as a rule well developed wings 
though there are some wingless forms. Most frequently they are 
to be found about decaying vegetable matter and fallen leaves but 
sometimes on windows. Little is known about the habits of most 
species and Brues, the leading authority on the family, has no doubt 
that much of interest awaits anyone who may undertake to study 
the varied habits of this group. Brues recognises 23 genera. This 
is an isolated group whose systematic position is unsettled and Dahl 
has contended that the Phoride show affinities with fleas. 
To the student of parasitology the larvae are of exceptional inter- 
est because some get their nourishment from dead and decomposing 
* An interesting account and plates of larvae, etc., will be found in: “ Beitrag. 
zur Biologie der Acroceriden”’ (Cyrtidew) by F. Brauer. Verh. Zool-Bot. Ges. Wien 
(1869) Vol. 19 p. 737. See also the same author’s later paper (1883) Denks. Ak. Wiss. 
Wien, Vol. 47 at p. 26 and p. 61. 
Wytsman’s ‘“‘ Genera Insectarum”’: Part 43. Phoride by C. T. Brues. There 
is ne a Monograph by Theodor Becker Abh. Zool.-Bot. Ges. Wien. (1901) Vol I. 
Heft 1. 
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