50 CULICIDJE [CH. 



CHAPTER VII 



FAMILY CULICID^: (GNATS OR MOSQUITOES) 



General Account. 



Definition. The Culicidae are slender flies easily distin- 

 guished from all other Nematocera by the presence of a row 

 of scales on the posterior margin of the wings. In addition, 

 the long projecting proboscis, and the plumose antennae of 

 the males are characteristic features. 



External anatomy. The head is small and subspherical ; 

 the occiput is always more or less covered with scales of various 

 forms. The eyes are large and reniform and may, or may not, 

 meet in the middle line ; in the living insect they are often 

 brilliantly coloured, but in preserved specimens these colours 

 usually fade. Ocelli are absent. The antennae are long and 

 slender, composed of 14 or 15 segments ; the basal segment 

 is large, round, and is sometimes provided with scales. The 

 second segment fits into a depression at the apex of the first, 

 and the remaining segments are all more or less elongated 

 cylinders. Just above the base, or in the middle, of each 

 segment arises a whorl of long thick hairs, which are some- 

 what scanty in the female, but in the male are so thick-set 

 as to give the antenna the appearance of a bottle-brush ; 

 in addition, the last two segments of the male antenna are 

 nearly always more elongated and nearly bare. 



The mouth-parts consist of the following appendages : 



(i) A pair of mandibles, each of which is an extremely 

 delicate chitinous blade adapted for piercing the skin. In the 

 male the mandibles are absent (Figs. 26 and 27). 



(ii) The first pair of maxillae, generally known simply as 

 the maxillae, are extremely fine stylets usually longer than 

 the mandibles. In the male the maxillae are sometimes rudi- 

 mentary. From the outer side of the base of each maxilla, 

 arises a maxillary palp, the form of which varies according to 

 the sex. 



