116 THE EARLY STAGES OF TABANID^ 



inches upwards, in which the water moves but slowly. Such rocks 

 occur only here and there, in the mile or so of stream searched, only 

 three rocks bearing traces of having been used by this tabanid for 

 purposes of oviposition being found. On one of them were the re- 

 mains of several hundred egg masses lining a small crack in the face 

 of the rock from 2 to 3| feet above the water level. As none of the 

 fresh egg masses found were situated more than 15 inches above 

 water level, these old masses had probably been deposited when that 

 level was higher. Altogether seven females were taken in the act of 

 ovipositing, and several more were seen. No particular time of the 

 day seems to be chosen for the act; one was found ovipositing at 

 11.40 a.m. and another at 4.40 p.m., and unlike Tabanus higuttatus 

 Wied., the only other horse-fly King has observed ovipositing in the 

 field, this tabanid does not lose her natural wariness while engaged 

 in depositing her eggs. In fact, she is often more difficult to capture 

 then than when merely sunning herself on a rock. 



The egg masses, figured by King (Plate 1, Fig. 20), vary in size, 

 and no count of the number of eggs contained was made, but the 

 average mass is believed to consist of about 500. When freshly laid 

 the mass is glistening white and can be seen from a considerable 

 distance, but within a few hours it takes on a mottled gray hue 

 which so closely resembles the color of the rock that it is not easily 

 detected. While the fly is occupied in laying her eggs, numbers of a 

 tiny Hymenoptera assemble and proceed to add their eggs to the 

 mass, continuing to do so after the fly has gone. From some twenty 

 egg masses collected from the rocks about equal numbers of this 

 egg parasite and of the tabanid larva were obtained. Specimens of 

 these Hymenoptera were sent for identification to the Scientific Sec- 

 retary of the Entomological Research Committee. They proved to 

 be a new species of Chalcidas, and have been described by Mr. J. C. 

 Crawford, of Washington, under the name of Telenomus kingi (foot- 

 note to King's paper, by Mr. Guy A. K. Marshall) . 



One horse-fly''^ taken in the act of ovipositing completed her egg 

 laying in a collecting box on the evening of April 13. These eggs had 



^^ King frequently uses the Arabic word "seroot," for horse-fly, by which the 

 flies are known in the Sudan. 



