152 



where malaria had occurred. Few infections occur in the summer 

 months, but a sharp rise begins in September. In the winter of 1920 

 a rapid fall occurred in December, whereas in the winter of 1921 this 

 began in January 1922. Mosquitos found infected in December and 

 spring only harbour a residual infection in the stomach cysts, sporo- 

 zoites being absent. The temperature in winter and early spring is 

 below 15° C. [59° F.], so that mosquitos cannot contract infection. 

 In summer probably more individuals become infected, but they 

 escape out of doors and are lost among those from animal quarters 

 and members of new generations. 



The importance of killing adult mosquitos in malarial dwellings from 

 September to December is obvious, but there is no advantage in doing 

 so in summer. 



Lamborn (W. a.). Some Problems of the Breeding-places of the 

 Anophelines of Malaya : A Contribution towards their Solution. 



—Bull. Ent. Res., London, xiii, pt. 1, May 1922, pp. 1-23, 1 fig., 

 6 tables. 



From a review of previous literature and the author's own investi- 

 gations, it is evident that no conclusions sufficiently valid to be of any 

 practical value can be drawn from the characters of the environment 

 as to the species of mosquito larvae likely to be found in a given 

 breeding-place. Anophelines are selective to a high degree, but this 

 tendency depends apparently on factors other than the mere environ- 

 ment of the breeding-place. In attempting to solve this problem with 

 regard to the Anophelines of Malaya, the factors under consideration 

 were the presence of other mosquito larvae in the water, and its 

 odour and constitution. The investigation was largely restricted to 

 Anopheles minimus aconitus, which is one of the doniinant Anophelines 

 in the Malay States. From October to April, this species almost 

 outnumbered the larvae of seven others taken at the same time. Up 

 to the end of October there was an overwhelming dominance of this 

 species, after which a sudden relative increase of others occurred. 

 From a collection of 10,549 larvae from a very large artificial pond 

 about 50 yards square, used for cultivation of fish, only two individuals 

 of A. minimus aconitus were taken, although the collection was made 

 between October and April. The absence of reeds, the size of the 

 pond and depth of the water have apparently no bearing on the matter, 

 as these larvae have been found in other similar breeding-places. 

 It is supposed that some quality of the water affects the distribution of 

 A. minimus aconitus either directly or indirectly by influencing the 

 character of the food. It was hoped to determine the nature of this 

 quality by water analysis, but the investigations were interrupted 

 before any final conclusions were arrived at. The transference of newly- 

 laid ova into waters different from those in which they are usually 

 found did not prevent hatching. Under laboratory conditions the 

 larvae of various open country species could be bred to maturity in 

 natural media in which numerous examinations had constantly shown 

 the entire absence of the species under experiment. All common 

 Anophelines could be bred from the egg in a medium in which only 

 A . vagus existed in nature ; even the experiments with A . ludlowi 

 were successful, although this species is limited in the Malay States, 

 though not in Java, to the coastal region, owing to its preference for 

 brackish water. A. nmbrosus entirely disappeared from a breeding- 

 place as a result of clearing the surrounding bush, being replaced by 



