152 



been satisfied, the individuals have done their duty and have now only one thing 

 to do: to disappear and make room for new individuals. 



As well known the mouth parts and the sucking apparatus of the mosquitoes 

 have often been subjected to thorough investigations from Reaumur to our day. I 

 refer especially to the papers of Dimmock (1881), GrOnberg (1907), Leon (1904 

 p. 730 and 1911 p. 7), Macloskik (1888 p. 884), Mum (1883), Thomson (1905 

 p. 145), Wesche (1904 p. 28). A more thorough study of the mouth parts of the 

 different specimens is however still lacking. I have made slides of almost all 

 our species and studied them in preparations of Canada. There are really some 

 small differences in the different species; this especially holds good with regard to 

 the form and hair equipment of the labella? and to the number of saw teeth upon the 

 maxilla 1 ; but the differences are but slight and their constant number only to be 

 detected after very thorough investigation. 



Mating process. 



In the course of years, from 1760 (Godeheu de Rivelle p. 617 and Reai - 

 sum) and to our own day, many observations on the mating habits of the mosqui- 

 toes have been made. Most of them have been collected in the chapter upon mating* 

 habits in Howard, Dyar and Knab (1912 p. 120—132). 



It has been pointed out that in many species the males congregate in swarms, 

 but that there also exist species in which no swarm-congregation takes place. Even 

 the manner in which the swarms are formed, their position in the air, the size 

 and the behaviour of the single individuals of both sexes, differ from species to 

 species. Of fundamental significance is the observation that the attitude assumed 

 during the copulatory act differs according to the structure of the claws of the 

 female: "In forms with simple claws (Culex, Anopheles) the position is end to end. 

 the pair facing in opposite directions. The forms in which the female claws are 

 toothed, copulate face to face, clasping each other with their claws" (Howard, Dyar 

 and Knab 1912 p. 121). 



Commonly it is only the males which congregate in swarms, whereas the 

 females make their way singly into the swarms from the outside. There are also 

 species where the males as well as the females form swarms, and the pairing takes 

 place when the single individuals drop out from the swarms and unite. Commonly 

 the swarms congregate near the ground and often over prominent objects: hay 

 stacks, isolated trees, church-steeples etc.; they often follows persons, walking over 

 the meadows and grow thicker and thicker as the person walks along. It has been 

 noticed that persons have been surrounded by swarms of females not reaching 

 above the knees, and with swarms of males around their heads. The swarms emit 

 high vibrating notes, often two distinct ones, corresponding to the two different 

 swarms and to the dancing up and down of the mosquitoes. A few species, f. i. 

 Aedes ealopus, pair in the rooms of our dwellings and these species only can be 

 hatched and studied through many successive generations. The swarming of the 



