Mosquitoes 



from above and silvery white from below, the latter color being 

 due to the water film. The eggs are laid early in the morning 

 before dawn and in warm weather will hatch by two o'clock on 

 the afternoon of the same day. The larvae are active little crea- 

 tures known as wrigglers which are so often to be seen in rain- 

 water barrels and horse troughs. The anal end of the body is 

 provided with a long respiratory tube into which two large air 

 vessels extend quite to its tip, where they have a double orifice 

 which is guarded by four flaps. This tube issues from the eighth 



Fig. 59. — Culex pungens: Egg mass, with enlarged eggs at left and young 

 larvae below — enlarged. (Author's illustration. J 



segment of the abdomen. The ninth segment is armed at the tip 

 with four flaps and six hairs. The flaps are gill-like in appear- 

 ance, though they are probably simply locomotary in function. 

 The mouth parts are curiously modified and are provided with 

 long cilia which are kept constantly in vibration, attracting and 

 directing into the mouth minute particles of animal and vegetable 

 matter which are to be found in the water. The wriggler remains 

 at the surface of the water when breathing through its respiratory 

 tube but descends when seeking for food. It undergoes three 



105 



