Exhibition of ‘Autogenous’ Characteristics by a British Strain of Culex pipiens L+ (Diptera, Culicidæ)

A FEW years ago, Roubaud¹, De Boissezon² and Huff independently directed attention to the fact that females of certain strains of C. pipiens were remarkable, not only in being able to breed, under suitable conditions, throughout the winter, but also in being able to lay fertile eggs without a preliminary meal of blood. Roubaud considers these unusual characteristics to be indicative of a distinct, `autogenous' race of C. pipiens, which thrives (in his opinion) exclusively in urban areas where artificially-heated buildings are common. De Boissezon, on the other hand, denies the existence of such a race of C. pipiens, and asserts that the biological peculiarities in question may be caused to manifest themselves in any strain of C. pipiens (whether town- or country-bred) merely by giving the larvæ plenty of rich food and keeping them warm.