ON INDIAN PARASITIC FLIES. 
adaptations which have been developed by this family in connection 
with their parasitic habits. On emerging from the pupal stage the 
insect, when its wings and body have hardened in the air, must seek a 
host on whose blood it will feed and on whose body it will dwell. 
For this purpose the wings are used ; but once established on the cattle 
these flies rarely use their wings except to move from one part of the 
host’s body to another or to fly a short distance to another member 
of the herd. They cling in clusters to the softer parts of the body 
between the legs and beneath the tail. They move slowly and 
laboriously, often side-ways with crab-like motion. So far as is 
known the female deposits her single larva on the ground in places 
■frequented by cattle. The larva is incapable of movement, and forth- 
with pupates, whilst the mother returns to the host to suck more 
blood and nourish another single larva. How many larvae are thus 
successively produced is unknown, but probably they are compara- 
tively few in number. This is one of the contrasts between this 
present family and other usually prolific Diptera. The ovaries are 
greatly ixiodified. A single large egg is produced at a time and the 
larva remains in the distended oviduct. After extrusion the larva 
hardens by the excretion of chitin and it then resembles a small brown 
pea. Out of this emerges in due course another generation. There 
is no free larval life. Such is the cycle of life in H. maculata. 
The structure of H. maculata is typical of many other members 
of the family. The flies are of middle size with oval flattened bodies 
of a tough and coriaceous texture. This is an adaptation which 
enables the parasite to apply itself closely to the host’s body and to 
stand with impunity a certain amount of violence if the host tries 
to dislodge it. The head is small and not half the breadth of the 
thorax. The fly has a pair of large, oblong, compound eyes, but 
they are not prominent and the facets are notably small. There are 
no ocelli in this species, but some other Hippoboscids have simple 
eyes as well as the compound ones. The antennae are extremely 
short. The first and second joints are indistinct while the third 
joint is round and bears a bristle-like arista. The thorax is broad. 
The abdomen is slightly hairy, compact and leathery so that the 
sutures between the segments are indistinct. The sexes can be readily 
distinguished by the shape of the abdomen which in the male is 
linear, shorter and narrower than the thorax ; in the female it is 
oval, longer and broader than the thorax. 
We come now to the legs and wings which show modificatioirs 
connected with a parasitic and sedentary life. The legs are rather 
short, very stout and slightly bristly. The two posterior pairs are 
fixed wide apart. The tibiae are a little shorter than the femora ; 
the tarsi are half the length of the tibiae. Each foot terminates with 
imgues or claws which are long, stout, curved and bidentate. The 
