209 



Macfie (J. W. S.) & Ingram (A.). The Early Stages of West African 

 Mosquitos. v. Culex decens, Theo., and Cidex invidiosiis, Theo. — - 

 Bidl. Entom. Res., London, xi, no. 2, September 1920, pp. 105-112, 

 2 figs. 



In view of the diversity of opinion as to whether Culex decens and 

 C. invidiosus, both of which are widely distributed in British West 

 Africa, should be regarded as two distinct species or merely as two 

 forms of one species, the authors of the present paper have examined 

 a number of larvae and pupae of these mosquitos, and their character- 

 istic features are described and compared. Neither stage provides 

 any feature of differential importance, and it is therefore considered 

 that they should be regarded as varieties and not as distinct species. 

 It is proposed to retain the name C. decens for the species. 



Jack (R. W.). Some Notes and Remarks on the Bionomics of Glossina 

 morsitans. — Bull. Entom. Res., London, xi, no. 2, September 1920, 

 pp. 113-132. 



These observations on Glossina morsitans are of necessity of a 

 somewhat scattered and meagre nature, having been made during 

 brief visits to the fly-areas in Southern Rhodesia. It is hoped, however, 

 that the tentative views put forward may arouse interest among 

 other investigators and perhaps receive either confirmation or criticism 

 supported by actual observations. Lamborn, recording observations 

 in Nyasaland in 1915 [R.A.E., B, iv, 113], contends that the breeding 

 season of G. morsitans is at its minimum in July, and is at its height in 

 October, when the first rains may be expected. The author has 

 previov.sly remarked upon the marked difference in the distribution 

 of tsetse-fly in the dry and wet seasons. The type of haunt where the 

 fly is most numerous in the dry season consists of isolated areas of 

 low-lying grass land with some evergreen trees along at least some 

 portion of its margin ; here the grass-feeding animals concentrate 

 in large numbers and provide an ample food-supply ; such centres 

 might be regarded as first grade foci. In other favourable fly-areas, 

 fivers a,nd vleis may be much more prevalent, and intense concentration 

 of game and fly does not occur ; such areas might be termed second 

 grade foci ; while shady forests beside rivers where game is likely 

 to rest during the day or pass through for drinking purposes, and 

 where the bushbuck frequently makes its home, might be termed third 

 grade foci. As all kinds of animals seek shade during the heat of 

 day in hot weather, and as the fly also is dependent upon shade, fly 

 and game will tend to meet most frequently at the time of year when 

 shade is restricted. Provided, therefore, that the temperature is 

 suitable for breeding, the dry season should in general be more favour- 

 able to the fly. The dependence of the fly on large mammals for its 

 food supply, which is a theory accepted by most investigators, is 

 assumed throughout this paper. During the earlier part of the dry 

 season, in May, June and July, the coldest weather occurs, and there 

 is little doubt that the fly breeds less freely and that the pupal period 

 is more prolonged, so that the fly tends to be less numerous at that 

 time of year ; from August onward to the rainy season considerable 

 increase occurs ; with the advent of heavy and persistent rains the 

 (730) Wt.PlSoO 163 1,500. 12.20. B.&F.Ltd., Gp.11/14. A 



