CLASSIFICATION OF INSISTS. II 



From the keys included in the monograph, it appears that in 

 a number of cases, the larvae do not fall readily into the linear 

 arrangement of species adopted. 



From the foregoing much abbreviated and necessarily incom- 

 plete account, it is very evident that the larvae of mosquitoes 

 exhibit morphological differences approximating in extent and 

 fixity those characterizing the adults of the several species, and 

 that a scheme of classification based on larval structures runs 

 quite parallel with one based upon the imagines. In the case of 

 these insects the larvae show little differentiation in color and 

 other superficial details, and the recognition characters are 







essentially those of structure. 



In the pupae of mosquitoes the development of specific, generic 

 or tribal character is very limited and the identification of species 

 in this stage is not satisfactory. This is quite like the condition 

 in other groups of insects, although mosquitoes and related forms 

 are almost the only insects with an active pupa. The activity 

 of the pupa even in this case, is of course only a limited retention 

 of the great activity of the larva, necessitated by its adjustment 

 to aquatic life. The mosquito pupa breathes in a manner similar 

 to the larva, by a pair of spiracular tubes that are thrust above 

 the surface of the water, and although these organs emanate 

 from the anterior part of the thorax in the pupa, this stage must 

 remain highly active in order to perform its respiratory function. 



Much attention has also been given to the systematic descrip- 

 tion and classification of the larvae and pupae of the other more 

 generalized families of Diptera related to the mosquitoes by 

 Osten Sacken ('62), Brauer ('83), Hart ('95), Johannsen ('03- 

 '05) and numerous other entomologists. Quite recently Malloch 

 ('17) has gathered together this information relating to American 

 species and supplemented it with much new material. In these 

 other families, the larvae of the numerous species may very 

 generally be easily distinguished and tabulated upon much the 

 same type of characters as have been used for the mosquitoes. 

 The genera and families are also separable on the same basis 

 although the tabulation of the families is more difficult, indi- 

 cating that the natural affinities are w r ell indicated in the pre- 

 paratory stages. In fact the correlation between the two is 



