444 >^'EW YORK STATE MUSEUM 



Structural characters are of great importance in separating the 

 larvae of this entire group. Occasionally color is of considerable 

 service, yet it is always of secondary importance, since it is largely 

 influenced by environment. The general shape of the head, the 

 form of the antennae, and the position of the antennal tuft are all 

 of considerable service in identifying species. The cephalic setae 

 and the arrangement and character of the hairs on the body are also 

 of some value. 



The most prominent and peculiar structure is foimd in the air 

 tube, or, as it is termed by some, the siphon. This structure 

 exhibits a wide diversity in development, being entirely absent in 

 Sayomyia, very short in the Anophelinae, rudimentary in Corethra 

 and with widely varying proportions in the Culicinae. The general 

 form and size of this important organ is of considerable value in 

 identifying species and the presence or absence of setae, including 

 the modified peculiar pecten at the base of the air tube, afford 

 excellent characters for the separation of larvae. The hair tufts 

 on the dorsal or anterior portion of the air tube var}' considerably. 

 The air tube of Wyeomyia smithii Coq. is remarkable 

 because of the irregularly disposed setae occurring on all sides. 

 Culicada trichurus Dyar may be easily distinguished 

 by the anterior or dorsal series of hairs on the air tube, while 

 species belonging to Culiseta are at once recognizable by the unique 

 prolongation of the posterior pecten into a series of fine hairs 

 extending nearly to the tip of the air tube. The minor modifica- 

 tions of the more normal pecten teeth are also of considerable 

 service in the recognition of species. Many forms have one or 

 several teeth widely separated from the basal, nearly continuous 

 row of teeth found in others. 



The most interesting and valuable structure for classificatory 

 service, though unfortunately a somewhat inconspicuous one, is 

 foimd in the peculiar patch of spines or spinelike scales designated 

 as the comb. This is normally a lateral organ of the eighth segment 

 just beneath the air tube. It is usually triangular in form and may 

 be composed of from five to nearly loo individual scales or spines. 

 These are usualh^ attached to the unmodified skin, though occasion- 

 ally the}^ arise from the posterior border of a chitinized plate or are 

 even attached to a somewhat chitinized band. In either of the two 

 latter cases they are arranged in a single or double row. The spines 

 or scales themselves differ widely in structure, some being simply 

 thomlike in form, others with setaceous margins and some with 

 large apical and smaller subapical spines. A greater divergence 



