192 MOSQUITOES OF NORTH AMERICA 



II. THE CULICINES. 



We recognize eleven genera in the culicines, viz. : Culex, Carrollia, Lutzia, 

 Cidiseta, Mansonia, Psorophora, Aedes, Hcemagogus, Ortliopodomyia, Urano- 

 tcBuia, and Aedeomyia. A large number of species are represented, especially in 

 Culex and Aedes. We consider Culex to be evolutionally highest, its species being 

 closely related and often difficult to distinguish, the sexes showing marked 

 secondary differential characters, so that they are in general difficult to associate 

 correctly without breeding records. The genus is apparently now undergoing 

 modification and the species are in a state of plasticity. The larvae are inhabit- 

 ants of collections of water of a more or less permanent nature, the eggs 

 generally being laid in rafts. A group or subgenus (Microculex) inhabits the 

 water in the leaves of bromeliaceous plants, and has remarkably specialized eggs, 

 being laid in a mass of gelatin, each egg in its own capsule, much as in 

 Chaohorus and the Chironomidse. We do not, however, trace any relationship 

 therefrom, nor consider this a generalized character. Two other subgenera 

 (Culicella and Clvmacura) lay single eggs and are otherwise in a generalized 

 condition. 



Carrollia is a small group specialized from Culex; Lutzia contains a few 

 species whose larvae have acquired a predaceous habit and feed mostly upon 

 species of Culex, its own near relative. Culiseta and Mansonia are somewhat 

 connecting genera leading downward from Culex. The larvae are all inhabi- 

 tants of permanent collections of water and the eggs are laid in rafts. Culiseta 

 is an intermediate genus of few species, possessing many characters of Aedes, 

 but inclining in habits toward Culex. Mansonia is closely allied as adult, but 

 the larvae have acquired a peculiar adaptation, taking air from the roots of certain 

 aquatic plants by means of their peculiarly modified breathing-tubes, and never 

 coming to the surface. 



The following three genera are somewhat less specialized than the foregoing, 

 but have pursued a different course. The larvae inhabit pools of a temporary 

 nature, the eggs being laid singly and adapted to withstand dessication. This 

 habit has induced various modifications in all stages of the insects. The modifi- 

 cation of the eggs has been alluded to : the larvae develop with great rapidity ; 

 the females have a different shape of abdomen adapted for laying the single eggs. 

 They pass through the winter or dry period, according to the region inhabited, 

 in the egg state instead of that of adult or larva. They are thus enabled to 

 occupy territory unadapted to support Culex and allies, provided only that 

 water shall accumulate at certain periods to enable larval development. The 

 eggs can survive long periods of drought that would be fatal to the Culex adults. 

 Our first genus, Psorophora, contains two groups, one with larvse of predaceous 

 habit, developed from the other group and preying upon it. Aedes itself is our 

 largest genus, exhibiting the characters above described. The species are 

 numerous in temperate and arctic latitudes as well as arid districts, their pe- 

 culiar habits enabling them to withstand the rigors of an arctic winter as well 

 as the drought of a desert summer. Hcemagogus is a small group of tropical 

 distribution in which the characters resemble Aedes, but the special habits are 

 not well evolved. There is a remarkable correspondence with the Sabethini in 



