102 



MOSQUITOES 



needed to liold it. It requires an effort, in fact, for the 

 Anopheles larva to descend (which it apparently never 

 does up to the period of the final larval staofe, except 

 when alarmed), while it requires an efi'ort for the Culex 

 larva to ascend. 



Structurally the differences between the half-grown 

 larvpp of Culex and Anopheles- are well shown in Figs. 19, 

 19a, and 20. The g-roat size of the head of Culex, as con- 

 trasted with the small head of Anopheles, is a most strik- 



Yi(\. 20. — Half-grown Larva of Anopheles waculipennis ; enlarged. 

 (Author's illustration.) 



ing difference. The very long respiratory siphon (as Miall 

 calls it) of Culex contrasts markedly with the short one 

 of Anopheles. The arrangement of the hairs is entirelj' 

 different; the branching of the hairs of Anoi)heles, as 

 contrasted with the simple hairs of Culex and the little 

 paired star-shaped (apparently branchial) tufts on the 

 dorsum of Anopheles, is entirely absent with Culex. 

 The fla]is at the tail end of the body are similar in num- 

 ber, but are held in a somewhat different ])osition. 



