RACES OF MOSQUITOES 291 



An extensive literature has grown, during the past few years, 

 around the subject of biological races in mosquitoes. The pre- 

 valence of " anophelism " without malaria in many districts has 

 formed the basis of the idea that races may exist which vary in 

 ability to transmit the malaria Plasmodium and in diverse other 

 biological features. Thus Anopheles maculipennis labranchice lays 

 a maculated grey egg, is especially prevalent in human habitations 

 and does not undergo complete hibernation. This race occurs 

 wherever malaria is prevalent in Europe, and its larvae are stated 

 to tolerate brackish water. Anopheles maculipennis messece lays 

 eggs marked with two transverse black bars : it frequents stables, 

 undergoes hibernation and is the predominating form in non- 

 malarial districts. Its larvae are stated to show preference for 

 fresh water. Differentiation of two races upon the foregoing 

 criteria as stated by Hackett, Martini and Missiroli (1932) has 

 been confirmed in the main, but according to Roubaud and 

 Gaschen (1933), the so-called maxillary index or, in other words, 

 the number of serrations on the maxillary stylets is a better 

 criterion than the egg-characters already alluded to. More 

 recent work by Missiroli, Hackett and Martini (1933) has led to 

 the conclusion that in addition to the two races mentioned, three 

 or possibly four others also occur. These differ, among other 

 features, in their feeding habits : thus, labranchice and sacharovi 

 are the important malaria carriers : messece and atroparvus 

 normally resort to animal hosts, but attack man in the absence 

 of the latter, while melanoon and typicus have no significance in 

 connection with malaria transmission. 



The researches of Roubaud and his co-workers, published in a 

 number of papers between 1929 and 1932, have shown that in 

 France there are two definite biological races of Culex pipiens. 

 These races are characterised as follows : (1) C pipiens pipiens, 

 which undergoes cyclical hibernation, does not oviposit without 

 blood-meals (anautogeny) and requires a large area for pairing 

 (eurygamy). (2) C. pipiens autogenicus, which does not hibernate, 

 but breeds continuously throughout the year. Females of this 

 race lay fertile eggs, without partaking of any food as adults, the 

 ova maturing at the expense of food-reserves accumulated during 



