8 



GNATS OR MOSQUITOKS — CHAPTER I 



are due to variations in the coloration of this scaly coating ; 

 and as these are very easily rubbed off, caution is necessary 

 in comparing them with descriptions. 



The tinting of the chitinous body wall itself is spoken 

 of as " ground colouring," and in insects which are provided 

 but scantily with hairs, this may be arranged in sharply 

 defined and brilliant markings, as, for example, in many 

 midges, but in the Cidicid(^ it is usually of a nearly uniform 

 dull tint, and at most shares only in the production of their 

 markings by showing through, between tracts of scales, in 

 the form of symmetrical bare lines and patches. 



Fig. 3.— Head op Female Culex. 



a, thorax ; 6, neck ; c, uape ; d, occiput ; e, vertex ; /, eyes ; g, frons 

 h, clypous ; i, antennae ; k, palpi ; I, proboscis. 



In descriptions of Mosquitoes it is not uncommon to 

 find the coloration of parts qualified as " when denuded," 

 and where this is the case it must be understood that it is 

 the ground colour that is referred to. 



In Anojphelea, as a rule, there are few or no scales on 

 the abdomen, and its coloration is mainly ground colour. 

 Their appendages, on the other hand, are exceptionally 

 densely scaled. In Corethra, again, the appendages, though 

 very hirsute, are so mainly through the abundance of hairs, 

 but in all genera of gnats the armature of the wings is 

 entirely composed of scales. 



