﻿252 L. NICHOLLS — SOME OBSERVATIONS ON THE BIONOMICS AND BREEDING- 



Developmental stages of A. argyrotarsis and A. albimanus. 



Adults. — The very closely allied Anopheles argyrotarsis and A. albimanus are 

 easily distinguished from each other by the last tarsal joint of the hind leg being 

 almost entirely black in A. albimanus, while, except for the claws, it is white in 

 A. argyrotarsis. This is the only characteristic by which they can be readily 

 separated with the naked eye. Magnification shows one or two other differences, 

 but these vary to some extent, and are often not easily observed in specimens 

 which have been kept for any length of time. 



Larvae. — There is a bewildering number of small variations in colour, mark- 

 ings, relative size of parts, and hairs of Anopheline larvae of the same species, so 

 that it is advisable to mention some of these and the manner in which they are 

 produced. 



The larvae suffer from a number of diseases due to Protozoa (chiefly 

 Vorticellidae) and vegetable organisms such as diatoms, algae and fungi. 

 If a larva has much growth of fungi or algae upon it, or Protozoa within or 

 adherent to it, it will present an unhealthy appearance (fig. 1, c); its movements 

 will be sluggish ; its relative proportions lost ; numbers of its hairs will be 

 altered, or entirely lacking ; if it survives (and the majority do not), a long period 



Fig. 1. — Larvae of Anopheles {Nyssorliynchus). 

 (a) A. albimanus, Wied., drawn from healthy larva of 6 mm. ; (b) A. argyrotarsis, R.D., 

 drawn from healthy larva of 6 mm. ; (a) a diseased larva, 5 mm. in length, covered with algae 

 and thousands of Vorticellae ; (d) A. argyrotarsis, lateral view. 



