58 



MISC. PUBLICATION 336, U. S. DEPT. OF AGRICULTURE 



Megarhinus, are recognizable on sight, and in the larval stage 

 practically all the species fall naturally into the generic groupings, 

 as may be noted in the larval key. 



The external characters and the terminology of the parts employed 

 in the descriptions of adult mosquitoes are shown in figures 14, 15, 

 and 16. 



In preparing to identify a mosquito specimen, a preliminary exam- 

 ination should be made at a comparatively low magnification, to note 

 the more obvious markings of the tarsi, proboscis, thorax, etc. T\ r ith 

 experience the approximate position of the insect, frequently both 



genus and species, is 

 recognized from this ex- 

 amination. In the 

 Southern States, after 

 the Anopheles are sep- 

 arated, nearly all the 

 species having the legs 

 unhanded and the meso- 

 notmn unmarked are 

 Gulex, Theobaldia, or 

 Deinoeerites. The spe- 

 cies of banded-legged 

 Culex are extremely 

 rare in this area. In the 

 species of all the other 

 genera, except Psoro- 

 phora cyanescens a n d 

 Aedes cmereus, some of 

 the tarsal segments are 

 ringed with white, or 

 the mesonotum has bi- 

 colorous scaling in defi- 

 nite patterns. 



Aedes and Psoro- 

 phora females can near- 

 ly always be distin- 

 guished from those of 

 other genera by the ta- 

 pered end of the abdo- 

 men, as shown in figure 

 IT. This is a very use- 

 ful character to remem- 

 ber in working with the 

 keys, but it has not been employed as the principal means of sep- 

 arating these genera because it is not always definite. (Particu- 

 lar care must be taken in examining specimens filled with blood 

 or ova.) As shown in the generic key, Aedes and Psorophora are 

 distinguished also from the other mosquitoes, except Mansonia titil- 

 Jans, by the presence of postspiracular bristles. The Psorophora are 

 distinguished from Aedes by having spiracular bristles as well, al- 

 though it is frequently very difficult to see them. In Psorophora, 

 however, the dorsal or lateral pale scaling of the abdominal seg- 

 ments is apical or diffuse, whereas in Aedes it is generally basal or 

 extends from the base. In Psorophora, subgenus Grabhamia, the 



Figure 14. — Female mosquito (Aedes sollicitans), 

 with names* of the parts. 



