80 REPORT OF THE AGRICULTURAL RESEARCH INSTITUTE 



have commented on the difficulty in inducing bred females 

 to suck blood (see Patton & Cragg, Text-book of Medical 

 Entomology, page 295). 



Tabanus albimedius. Flies emerge about the end of 

 February. Egg-masses of this species were observed along 

 the river bank by the middle of March. Egg-laying is at its 

 height thence onwards until the middle of April, whilst very 

 few egg-masses could be found after the beginning of May. 

 A second brood of this fly emerges about the end of June and 

 a third brood in October, the descendants of these again 

 appearing in February-March. These eggs are parasitized 

 by a small chalcidid, of which 166, 78; 105 and 138 indivi- 

 duals emerged from four egg-masses; these parasites were 

 bred and the life-cycle from egg to adult noted to be eight 

 days in the case of males and nine days for females, the 

 males, which are yellowish and smaller than the black 

 females, thus emerge one day earlier and move about on the 

 parasitized egg-mass in eager expectation of the emergence 

 of the females; on this happening, coupling commences 

 immediately and oviposition follows a few hours later. 

 Sixty parasites were bred from one fresh egg-mass of '/'. 

 albimedius after this had been subjected to the oviposition 

 of one fertilized female parasite; the total number of eggs, 

 which may be laid, may, however, be larger, as indicated by 

 the number of parasites reared from individual egg-masses. 



Egg-masses of T. nemocallosus were also noted to be 

 subject to attack by a parasite of a different species, but no 

 parasites were found in egg-masses of T. bicallosus. 



Tabanus striatus seems to have three broods annually 

 as in the case of T. albimedius, the flies emerging about the 

 end of February, June and October. 



Tabanus sanguineus, on the other hand, was not observ- 

 ed on the wing until the end of May, and T. hilaris. which 

 is common during the Rains, also did not appear until the 

 end of May. 



Chrysops stimulans oviposits on grass growing in 

 shallow water by a river bank during the last week in 



