712 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXVIII. 
2. CavicolcE. Larvse found in the frontal sinus, nasal cavity and 
throat of Covicarnia ^cattle, sheep and other hollow-horned rumin- 
ants). Tylopoda or camels, Cervidce (the deer family), Probcscidea 
(elephants). The Indian genera are (Estrus and Cephelomyia. 
3. Cuticolce. Larvae found under the skin of Gavicornia, deer, 
the horse family and rodents. Hypoderma, so far as I can discover, 
is the only recorded Indian genus. This is the group to which the 
warble-flies belong. 
Brauer enumerated sixteen genera in the whole CEstrid family 
and about half a dozen more have been established since his day. 
The adult flies belonging to this family are not difficult to recognise. 
They are fairly large and thick-set flies with big heads, of which the 
lower part is inflated, giving a sturdy appearance. The short, three- 
jointed antennae are sunk in the front of the head and hardly visible. 
The compound eyes are not prominent, and there are also ocelli, or 
simple eyes. The abdomen is short, conical and often hairy, somewhat 
like that of a bee. The veins in the wings are like those of house- 
flies and others of the Muscid stock, from which the CEstrids are 
doubtless descended. The second pair of wings (as in all Diptera) are 
represented by small balancers called halteres. In many CEstrid 
flies the halteres are protected by scales, usually large, which are 
known as squamae or tegula-. 
Much controversy has raged as to the manner in which the larval 
parasites reach their abiding place in the host’s body. It is now 
generally believed that the eggs, or young larvse, are, with some 
possible exceptions, taken into the mouths or nostrils of the animals 
which they infest, and so proceed, respectively, into the stomach, 
nose, throat and frontal sinus, or bore a way through the tissues 
of the body to the skin. 
1. Gastricolce. — The genus Gastrophilus has many species and a 
world-wide distribution. All are parasites of horses, wild asses and 
zebras. These flies are therefore restricted as regards geographical 
distribution by that of the Equid.ee. Several species are common 
wherever men keep horses, and their larvae are the horse-bots well 
known to grooms and veterinary surgeons. Gastrophilus equi Fab. 
one of the typical species is widely distributed in India. The female 
buzzes about horses during the hot hours of the daj^ Hovering a 
moment, she deposits a yellowish conical egg which adheres, like the 
nit of a louse, by its narrow end to the hair. This egg remains se- 
curely attached, owing to a viscid matter which is deposited at the 
same time. The fore legs, which are most accessible to the horse’s 
tongue, arc as a rule the parts selected. The flies are somewhat hairy, 
with fawn-coloured faces and blackish thorax. The abdomen is 
mottled yellow, with darker brown irregular blotches. The abdomen 
of the female ends in a long ovipositor, which is doubled beneath 
