

lo. 



II. 



ORDER DIPTERA: THE NEMATOCERA, ETC. 47 



(Minute fragile midges; wings commonly with only three longitudinal 

 veins = Cecidomyidce. 



Not abnormally delicate and fragile ; wings usually with numerous 

 veins = g_ 



/Ocelli present = n 



\ Ocelli absent = lo. 



(Coxae elongate ; antennas usually elongate ; all the tibise end in 

 spurs = Mycetophilida. 



Coxae short ; antennas usually shorter than the thorax 

 = Bibionidce. 

 /The costal vein extends all round the wing = Dixidce. 



iThe costal vein stops at or near the tip of the wing = ii. 



'Gnat-like flies with long slender legs ; antennae filiform, often with 

 whorls of hairs = ChironomidcE. 



Thickset flies with stout legs ; antennas stout and stiff", hardly 

 longer than the head, and never having whorls of hairs ; wings 

 remarkably broad = Simuliida. 



Of the twelve families that constitute the section Nemato- 

 cera, only four are known to include species that suck blood 

 and attack man. There is good reason to believe that with 

 most of these species the females alone have this habit ; in 

 many cases, indeed, it is certain that the male can not depend 

 upon blood, as its mouth-parts are not capable of piercing 

 epidermis. 



The four families which are thus of interest to the medical 

 officer are: — 



(i) CwAV/iafe or Mosquitoes (p. 48). In the great majority 

 of the species of this large and cosmopolitan family the 

 females have mouth-parts made for piercing (Fig. 2), and 

 therefore are, or may be, blood-drinkers. 



(2) PsychodidcB or Moth-like Midges (p. 115). In this 

 family the species of only one genus, Phlebotomus have pierc- 

 ing mouth-parts and are notorious blood-suckers. The 

 species at present known are about a score in number, and 

 have been recorded in all the great zoological regions except 

 the Australian. In some species, if not in all, the mouth- 

 parts of the male are quite as formidable as those of the 

 female. 



(3) ChironomidcE, or Midges (p. 120). Only a few species of 

 this enormous family are specialised for a diet of blood, and 

 these are all of minute size and belong to the subfamily 

 Ceratopogoninm, which is represented in all parts of the world. 



