108 



HEPOKT OF THP: ENTOMOLOGICAL SECTION 



metatarsi, thin and bent ; mid legs with short metatarsi, second tarsal normal, third 

 bent under the fourth and projecting with two dark unequal claws, like ungues and with 

 two lateral leaf-like processes on each side of the claw's, ungues on terminal segment equal 

 and simple ; hind legs with the tibiae with five basal bristles in a row, contracted at 

 one-third their length, where there is a tuft of five long orange to brown spines of nearly 

 equal length, three together bent apically and also a sixth much longer spine, near the 

 middle of tibia is a single long spine ; metatarsi and tarsi thin, ungues equal and simple. 



Wings much as in the ^ ; the first fork-cell much smaller than the second, its base 

 much nearer the apex of the wing, its stem nearly three times the length of the cell, stem 

 of second fork-cell about one-and-a-half times the length of the cell ; posterior cross-vein 

 longer than the mid, about one-and-a-half times its own length distant ; second long vein 

 close to first. Genitalia small and hidden ; claspers thick and blunt, basal lobes triangular. 



Length, 3 mm. 



Habitat. — Sudan, Bor to Mongalla, 21 specimens including 3 J''s (H. H. King). 



The female of this species was described by Mr. Theobald in the Third Report of these 

 Laboratories under the name of Uranotienia paltidocephala sub. sp. cieruleus, but later, 

 on examining the male, he raised it to the rank of a species. 



The Conteol of Mosquitoes 



Pump irriga- 

 tion more 

 dangerous 

 than sakias 



The control of mosquitoes on artificially irrigated farms is a matter of considerable 

 importance, bearing as it does directly on the subject of the health of those living in the 

 neighbourhood. Without mosquitoes the northern provinces are — except for the heat — 

 healthy, but if anophelines are allowed to exist in any numbers, malaria at once becomes rife. 



The ordinary native-owned cultivation is dependent for its water-supply on a sakia — 

 a cumbrous, wooden water-wheel, turned by cattle-— and very few mosquitoes breed out on 

 these sakia-lands. The volume of water raised is so small that the owner cannot afford to 

 allow any of it to go to waste. The floors of the gudwals — as the water-channels are 

 termed— are usually above the level of the surrounding land, and consequently when the 

 sakia ceases to turn, the gudwals run dry. The only breeding-places provided for mosquitoes 

 under such conditions are occasional puddles among the grass growing on the sides of the 

 gudwals, due to unsuspected leaks. 



The water used in irrigating a farm of from a few hundred to several thousand feddans 

 is raised by means of pumps, worked by engines, and in this case a comparatively large 

 volume of water has to be dealt with. The water is conveyed from the pumps by a main 

 canal from which open smaller canals. From these canals the water passes along large 

 gudwals, and from them by smaller ones directly on to the land. Each canal and gudwal 

 is, roughly, at right angles to those with which it connects. There may be many canals 

 and gudwals of various sizes, and when a heavy weight of water has to be supported by 

 earthen banks, leakages are bound to occur. The floors of the gudwals — which are always 

 much larger than any used on sakia-land — are generally below rather than above the 

 level of the surrounding land, and these water channels cannot therefore be emptied. 

 Consequently, when the gudwal is not in use, the water in it remains stagnant until it 

 either soaks away and evaporates — a process which may occupy several weeks — or the 

 gudwal is used again. In some localities, owing to the chemical composition of the soil, 

 water is continually soaking through the canal and gudwal banks to form little pools on the 

 other side. A bank of this nature is known as a " weeping" bank. The canals invariably 

 contain numbers of small fish, and, moreover, the water in them is usually moving, so there 



