THE C03I3ION MOSQUITO 



71 



is uot known, but which may possibly function as gills 

 while the larvse are very young, and are certainly of use as 

 swimming organs. When 

 the breathing tube is at the 

 surface of the water the 

 body of the wriggler ex- 

 tends down below the sur- 

 face at more or less of an 

 angle with the water sur- 

 face, and its mouth-parts, 

 as just stated, are constant- 

 ly in vibration, bringing 

 into its mouth any minute 

 particles which float in sus- 

 pension in the water. Oc- 

 casionally it descends to 

 the bottom, jerking its body 

 violently from one side to 

 the other. The flaps at the 

 end of the body undoubt- 

 edly assist in this motion. 

 The jerking motions are 

 not so evident when the 

 larva or wriggler is de- 

 scending as when it be- 

 comes necessary for it to 

 ascend once more ; in other 

 words, its specific gravity 

 seems to be greater than that of the Avater and sometimes 

 it can be seen to descend without effort, simply sinking 



Fig. 9. — Full-grown Larva of Culex 

 pungens ; enlarged. (Author's il- 

 lustration.) 



