MOSQUITOES AND FLEAS. 



13 



sipbon reaches the surface, fresh air flows into its tracheie, and the 

 physical properties of the so-called surface film of the water assist it 

 in niaiutaiuing its x)Osition. 



lu the first edition of this work the writer erroneously attributed an 

 error to Prof. L. G. :\liall in regard to the ninth body segment with its 

 terminal flaps. This was due to a wrong reading of Professor Miall's 

 accurate book on aquatic insects. 



The respiratory tube takes its origin from the tip of the eighth abdomi- 

 nal segment, and the very large tracheje can be seen extending to its 

 extremity, where they hav^e a double orifice. The ninth segment of 

 the abdomen is armed at the tip with four flaps and six hairs, as shown 

 in tig. 4. These flaps are gill-like in appearance, though they are prob- 

 ably simply locomotory in function. With so remarkably develoi)ed an 



Fig. ^.—Ctdez pungens: Head of larva from below at left ; same from above at right — greatly enlarged 



(origmal). 



apparatus for direct air breathing there is no necessity for gill struct- 

 ures. Easchke^ and Hurst- consider that the larva breathes both by 

 the anus and by these gill flaps, as well as by the large tracheii^ which 

 open at the tip of the respiratory tube. Raschke considers that these 

 trachene are so unnecessarily large that they possess a hydrostatic 

 function. The writer is inclined to believe that the gill flaps may be 

 functional as branchial structures in the young larva, but that they 

 largely lose this oftice in later life. 



After seven or eight days, at a minimum, as just stated, the larva 

 transforms to pupa. The pupa, as has been repeatedly pointed out 

 with other species, diflers most pronouncedly from the larva in the 

 great swelling of the thoracic segments. In this stage the insect is 



^Raschke, Die Larve von Culex nemorosuSy Berlin, 1887. 

 2Hnrst, The Pupal Stage of Culox, Manchester. 1890. 



