240 TROPICAL MEDICINE AND HYGIENE 



For this purpose, some knowledge of insects in general, 

 and mosquitoes in particular, is essential in order to advise 

 as to economic prophylactic measures, and an outline 

 of the classification of insects, and the principles on 

 which insects are classified, are here given briefly. 



CLASSIFICATION OF DIPTERA. 



Suborder I. Orthorrhapha. The adult imago escapes 

 from the pupal case through a longitudinal 

 anterior or posterior T-shaped slit. As there 

 is no ptilinum, there is, in the imago, no 

 frontal lunule. Antennae usually project in 

 front of the head. 



They are divided into NEMATOCERA (thread-like 

 antennae) and BRACHYCERA (short antennae). 



NEMATOCERA. Antennae have many joints always 

 more than six ; the segments, except the one 

 at the base, are similar to each other ; palps, 

 usually four or five joints. 



Nematocera vera. Joints of the antennae are 

 long, and frequently have whorls of hairs, 

 legs long and slender, abdomen usually long, 

 e.g. y Culicidae (mosquitoes). 



Nematocera anomala. Antennae composed of 

 many segments ; but these are all short, and, 

 as a rule, without whorls of hair. The 

 abdomen is usually stout, and the legs are 

 shorter and thicker than in N. vcra, e.g.. 

 Simulidae, or sand-flies. 



BRACHYCERA. The number of true joints in the 

 antennae is less than six ; palps, one or two 

 joints. 



Brachycera vera. Third joint of antenna is not 



ringed, and usually terminates in a bristle or 



style, e.g., Asilidae, or robber-flies. 



Brachycera anomala Terminal joint of antenna 



composed of several short segments fused 



