THE MOSQUITO 



91 



certain and varying dangers. Out of 834 

 larvae and pupae caught in Cambridgeshire, 

 636 were small larvae, measuring less than 

 4 mm. ; 181 were large larvae, measuring 

 up to 7 mm. But only 17 pupae were taken. 

 There are other facts f 



which show that the 

 larvae under natural 

 conditions succumb 

 in very considerable 

 numbers. 



When the larva 

 is about to turn into 

 a pupa it comes to 

 rest, and now the 

 thoracic regions are 

 more swollen than 

 ever. Soon a dorsal 

 slit appears along 

 the larval cuticle 

 and the pupa slowly, but gradually, emerges 

 through this slit and leaves the larval chitinous 

 cuticle behind it. On first emerging, the 

 pupa measures about 6*5 mm., the head and 

 thorax making up one-third of this. During 

 the last larval stage many of the pupal organs 

 have been re-forming and are more or less 

 visible through the cuticle. The mouth parts 

 and limbs of the third stage — ^the future 

 imago — show no relation to those of the 



Fig. 23. — Side view of late pupal 

 stage of Anopheles maculipennis. 

 f. The stigma opening at end of 

 trumpet-like projections. (From 

 Nuttall and Shipley.) 



