FLIES: TWO-WINGED INSECTS. 



KEY TO THE 



FAMILIES OF DIPTERA 



(ADULTS) 



1. Flies of a leathery or horny structure, living as per- 

 manent, blood-sucking parasites upon warm-blooded 

 vertebrates; the young (larvae) are born when nearly 

 ready to pupate. Wings very often reduced or lacking. 

 PUPIPARA (p. 279). 



Flies of a softer structure, not living as permanent 

 parasites upon warm-blooded vertebrates in the adult 

 condition; egg-laying, rarely giving birth tojhatched larvae. 

 Wings very rarely reduced or absent 2. 



2. Antennae having numerous joints freely articulated 

 with each other (usually from 8 to 16). Wings usually 

 without discal cell; the anal cell rarely narrowed in the 

 border of the wing. Palpi as a rule with 4 to 5 joints. 

 Suborder NEMATOCERA 3. 



Antennae are usually composed of 3 joints, usually 

 with a differentiated style or bristle (the last joint some- 

 times annulated). Wings almost always with a discal 

 cell; the anal cell, if present, closed or much narrowed in 

 the border of the wing. Palpi never with more than 2 

 joints. Suborder BRACHYCERA 13. 



3. Wings with a spider-web-like secondary venation of 

 creased lines between the ordinary veins; slender, long- 

 legged species BLEPHAROCERID/E (p. 246). 



'Only the ordinary venation in the wings 4. 



4. Mesonotum divided into an anterior and a posterior 

 part by a more or less distinct transverse suture, which is 

 very often V-shaped. Legs very long and slender; body 

 and wings elongate, the wings sometimes with a discal cell. 

 Never small; often very large TIPULHXE (p. 236). 



Mesonotum not divided by a transverse suture. 

 Never very large, often small 5. 



5. A complete discal cell present; the costal vein much 

 thinned beyond the tip of the wing; wings usually spotted. 

 Medium sized, mosquito-like RHYPHID^:. 



No discal cell 6. 



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