DIPTERA 



the labrum so as to form 

 a canal through which 

 the food passes (Fig. 18) . 

 These several partsmay be 

 seen under the microscope 

 by placing the head of a 

 female in a drop of water 

 on a glass slide and press- 

 ing lightly on the cover 

 glass laid over it. The 

 favorite food of the female 

 is blood of any of the 

 vertebrates. The male 

 never bites and may be 

 distinguished from the 

 female by the antennae 

 which are much more 

 richly feathered. The 

 two chief genera of the 

 four hundred species of 

 mosquitoes are Culex and 

 Anopheles. In the female 

 of Culex, the palpi are 

 not more than a fourth 

 as long as the proboscis, 

 while in Anopheles, the 

 proboscis and palpi are 

 almost equal. The palpi 

 are quite long in the 

 males of both genera. 

 When at rest, the pro- 



