1 I I JtKI'OllT OV TllK KNTOMOIiOOlCAL SECTION 



Slat\ -hlack : dorsum of thorax covered with a thin j^'reyish bloom, striped with grey, 

 and clothed with minute, yellowish or whitish hairs ; dorsum of abdomen with a more 

 or less distinct, median, longitudinal stripe (composed of elongate, grey triangles, with 

 their apices directed forwards and truncate), between which and the lateral margin on each 

 side is a longitudinal series of very conspicuous and sharj)ly defined, oblique, oval, light 

 grey spots ; lower portion of front innnediately above antennie produced into a very 

 prominent, shining black, transverse protuberance, on the under surface of which the 

 antenntE themselves are situated. 



Although on a cursory examination Tahaiins mordax may easily be mistaken for 

 T. lencostomus, Lw., since the abdominal markings, in the female sex at any rate, are 

 identical in each case, the former may be distinguished from the latter by the great 

 development of the supra-antennal protuberance, and by the absence of an appendix to 

 the anterior branch of the third longitudinal vein. 



TiiJidiiii.f par, Walker 

 Plate UL, tigs. 6 and 8-13 



Occasional specimens of this tabanid are met with on the White Nile from Gebelein 

 southwards, but it is rarely noticed boarding river steamers in any numbers. In the 

 country behind Bor there were several small belts where females abounded but no males 

 were seen. These females spent their time resting among the vegetation, especially 

 the low dom palms, until some animal, such as a cow, ajjproached, when they would at 

 once fly off and attack it. They did not, however, seem to follow cattle very far. No eggs 

 could be found, though a careful search was made in all the places that were considered 

 Breeding likely to Serve as breeding grounds, so a number of females, gorged with blood, was placed 



experiments .^^ ^ breeding-cage in which was also a dish containing mud, water, and growing grass 

 and weeds. They fed on sugar and water and though the majority died within the first 

 two days, the survivors eventually produced three small batches of eggs. 



On some flowering bushes by Khor Felus, on the Sobat River, about seven miles from 

 its junction with the White Nile, several males were taken, feeding on the flowers. Only 

 two or three females were seen, but as tliere were no cattle grazing in the immediate 

 vicinity it is probable that they had gone afield in search of more satisfying food. 



The eggs, obtained as described above, were deposited on May 23 and 24, on the 

 undersides of the leaves of a water weed. Unlike the eggs of most members of the genus 

 Tahanits, they were not closely packed in a rounded mass, but placed vertically and 

 separately though in a cluster. i They hatched on May 30, and the tiny larvte were 

 divided into three lots and placed in glass basins containing mud, water and growing 

 grass. These basins, for purposes of reference, were lettered A, B and C. 



At the time when the eggs hatched, I was in the Sudd region, where it was impossible 

 to land and obtain any subterraneous insect larvas or tiny fresh-water crustaceans for 

 them, so they were oflered the expressed stomach contents of gorged female ticks— 

 liMpicephalm .s'tHKfs— taken from a dog. A few fed once or twice but the majority refused, 

 and all buried themselves in the mud. 



On Juno 11, the larva; from A wei'e transferred from mud to clean river sand and 

 water, and given freshly killed mosquito larvffi. They fed on these readily and grew 



apace, though at greatly varying rates. 



' The arrangement of the eggs in the cluster is not well shown in the tigure 



