34 
to note that no specimens of Hcematopota came to drink at the pools, 
so that the species of this genus cannot be destroyed by the method 
indicated. A layer of petroleum on the surface of the water is fatal 
to aquatic horse-fly larvae, just as it is to those of mosquitoes. 
Tabanidse deposit their spindle-shaped brown or black eggs closely 
packed in rounded or flattened masses, which are attached to the 
leaves and stems of rushes or " other smooth surfaces over water or 
wet ground " (Hart). The larvae are whitish soft-bodied grubs, and 
are found in water, in earth, or in decaying wood. In shape they are 
cylindrical, tapering at each end, with a small retractile head, and 
with the first seven of the eight abdominal segments each encircled 
near its anterior margin with a ring of fleshy protuberances, of which 
there are " two transverse dorsal, one lateral on each side, and four 
rounded ventral ones."* Horse-fly larvae are carnivorous, preying 
upon beetle larvae, snails, worms, etc. The pupa which is not unlike 
that of a Lepidopterous insect, remains stationary in the earth or 
water. 
Tabanidae are sometimes preyed upon by robber-flies (Asilidae) ; 
thus at Brockenhurst, in the New Forest, on July 14th, 1894, Colonel 
Yerbury took a female Machimns atricapillits, Fin., feeding upon a 
male Ckrysops ccecutiens, Linn., both of which specimens are now in 
the Museum collection. In foreign countries horse-flies are also "a 
favourite food of the fossorial wasps of the family Bembecidae. These 
wasps are apparently aware of the blood-sucking habits of their 
favourites, and attend on travellers and pick up the flies as they are 
about to settle down to their phlebotomic operations. "f 
In Illinois,U.S. A., a parasitic Hymenopteron (P/ianurus tabanivorus, 
Ashmead) has been bred from egg-masses of Tabanus atratus, Fabr., 
one of the largest and commonest of North American horse-flies, and 
in Austria an allied species {Phajiurus {Telenoimis) iabaui, Mayr) 
was bred by the late Professor Friedrich Brauer from the eggs of an 
undetermined species of Tabanus.% 
* Hart, 'Bulletin of the Illinois State Laboratory ot Natural History,' Vol. IV. (1895), 
p. 222. 
fD. Sharp, ' The Cambridge Natural History. — Insects: Part II.' (London : Macmillan 
& Co. : 1899). P. 482. 
X Hart, loc. cit., p. 245, and Ashmead, ibid., p. 276. 
