34 



to note that no specimens of Htrmatopota came to drink at the pools, 

 so that the species of this genus cannot be destroj-ed 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 larva: are whitish soft-bodied grubs, and 

 are found in water, in earth, or in decaying wood. In shape they are 

 cj'lindrical, 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 larv.ne are carnivorous, preying 

 upon beetle larvs, snails, worms, etc. The pupa which is not unlike 

 that of a Lepidopterous insect, remains stationary in the earth or 

 water. 



Tabanida; are sometimes prej-ed upon by robber-flies (Asilidfe) ; 

 thus at Brockenhurst, in the New Forest, on July 14th, 1894, Colonel 

 Yerbury took a female Machiinus atricapillits. Fin., feeding upon a 

 male Chrysops ccEcutie/is, Linn., both of which specimens are now in 

 the Museum collection. In foreign countries horse-flies are also "a 

 favourite food of the fossorial was]3s of the family Bembecida:. These 

 wasps are apparently aware of the blood-sucking habits of their 

 favourites, and attend on travellers and pick up the flies as the)' arc 

 about to settle down to their phlebotomic operations. "f 



In Illinois, U.S. A., a parasitic Hymenopteron {P/ianiirus tabanivoriis, 

 Ashmead) has been bred from egg-masses of Tabaiius atratus, Fabr., 

 one of the largest and commonest of North American horse-flies, and 

 in Austria an allied species {Phaniirus {Telfiiomiis) tabani, Maj-r) 

 was bred by the late Professor Friedrich Brauer from the eggs of an 

 undetermined species of Tabaiius.X 



* Hart, ' Bulletin of the Illinois St.ite Lalmratory nt Natural Ilistciry,' Vol. I\'. (1895), 

 p. 222. 



tD. Sharp, ' The Cambridge Natural Ili.'ilory. — Insects: Part II.' (London : Macmillan 

 & Co. : 1899). P- 482. 



I Hart, hi. at., p. 245, and Asbmcaci, i/'u/., p. 2;6. 



