MOSQUITOES 63 



least halfway round. When lying beneath the water film 

 the body is in a normal position. That is, the upper 

 side of the body is uppermost and the under side faces 

 the bottom of the jar. The head, however, is turned 

 just halfway round so that the under side is uppermost. 

 This is its customary feeding position. If for any rea- 

 son it attempts to swallow r a piece of food too large and 

 there is difficulty in getting it down, the head turns 

 back with lightning-like rapidity. All the time the 

 brushes of hairs about the mouth are in motion, bringing 

 to it particles of food. 



The duration of the larval stage, under normal condi- 

 tions with plenty of food, varies from twelve to fourteen 

 days. 



Pupae. The pupae of Anopheles are not strikingly 

 different from those of Culex to the unaided eye. 



The pupal stage of both males and females in the case 

 of A. punctipennis which the writer has carefully ob- 

 served lasts, with great regularity, just about two days. 

 At least it could not have varied more than a few hours 

 from this, as the adults were found in every case on the 

 second morning subsequent to the morning on which the 

 pupa3 were found. 



To sum up, then, the entire duration of the early stages 

 of Anopheles punctipennis in Mississippi under normal 

 conditions in July was sixteen to eighteen days. That 

 is, the egg stage was two days; larval stage, twelve to 

 fourteen days; pupal stage, two days. This indicates 

 that in a pool where these mosquitoes breed there can 

 be developed every sixteen to eighteen days a new lot of 

 adult mosquitoes. It further indicates that if such a 

 pool be treated with kerosene oil, it will need an applica- 



