102 HAROLD H. KING BIONOMICS OF 



Tabanus tj^niola, Palisot de Beauvois. 



This is the most common and most widely distributed Tabanid found in 

 the Angio-Eoyptian Sudan, and is the one most frequently accused of 

 causing the death of camels. On the White Nile it occurs as far north as 

 Dueim, and stray specimens, brought in by cattle, have occasionally been 

 taken in Khartoum. Often it will board a river-steamer, and being, like 

 other seroots, a vicious bloodsucker, will drive any animals travelling on the 

 'barges nearly frantic with pain. It will follow cattle and other animals long- 

 distances : on one occasion, after walking straight inland from the river for 

 ifive hours without seeing a single seroot of any kind, numbers of this 

 Tabanid in company with Tahanus ditceniatus, Macq., were found attacking 

 :a buffalo which they had doubtless followed from some fly-belt near or 

 through which the animal had passed. Males are rarely seen, though single 

 specimens will sometimes board a river-steamer, and early in June 1909 some 

 twenty or thirty of this species and the very similar Tahanus variahis, Walk., 

 were noticed on flowering shrubs by Khor Felus, Sobat river. 



Gorged females were taken in May on cattle grazing near Bor, and placed 

 in a breeding-cage with a dish containing grass and weeds growing in mud 

 -iind water. They were fed on sugar and water, and a few batches of eggs 

 were obtained. A single egg-batch was taken in May on a blade of grass 

 •overhanging a dried up water-pool near Kanissa wood-station, and a number 

 -of egg-batches were collected early in July from grasses and weeds over- 

 hanging rain-pools at Gebelein. 



The eggs are placed by the female fly on the upper side of a blade of 

 grass or some similar plant, and, with the exception of the single batch 

 taken at Kanissa wood-station, all those found were overhanoino- water. 

 An unfinished egg-batch in plan resembles an arrow-head. The eggs are 

 closely applied to each other and left bare, so the batch can easily be seen 

 \\lien freshly laid, owing to its shining white to yellowish white colour. 

 Prior to hatching the egg-mass becomes darker. 



The eggs obtained in the breeding-cage were laid on May 24th-25th^ and 

 1 atched on May 29th. The larvae were placed in glass basins containing mud, 

 growing grass and water, and were off"ered the expressed stomach-contents 

 of female ticks — Rlnpicepl talus simus — taken from a dog. They fed readily 

 on this until June 11th, when they were placed in clean river-sand and 

 water, and their diet changed to mosquito larvae. These mosquito larvss were 

 either killed, or laid living on the wet sand out of reach of the water, in 

 ^vhich position the Tabanid larvae were able to kill them. In water the 

 mosquito larvae were too active to be caught. On July IGth their food was 

 changed again to freshly killed and bruised earthworms, and these they also 

 eat readily. While still young they became vicious cannibals, and con- 

 sequently each larva had to be given a separate dish. They were brought to 



