Dipt era. 61 



ORDER DIPTERA 



{ANTLIATA, HALTERATA, HALTERIPTERA, 

 HAUSTELLATA.) 



Minute to moderate-sized, rarely large insects, usually with 

 good powers of flight; the hind wings replaced by small knobbed 

 structures (halteres): head usually vertical, freely movable; 

 antennae variable, frequently three-jointed and provided with a 

 sensory bristle (style or arista); mouth-parts suctorial; both the 

 prothorax and metathorax small and fused with the large meso- 

 thorax; wings membranous, veins and crossveins not numerous; 

 legs usually alike, the tarsi regularly five-jointed. Metamor- 

 phosis complete, the larvae almost always legless grubs or maggots, 

 frequently with the head retracted and indistinct; pupse with the 

 appendages more or less adherent, the body sometimes entirely 

 encased in a seed-like capsule (puparium). Food-habits variable. 

 Flies, Mosquitoes, Gnats, Midges. 



1. AntennfE generally longer than the thorax, usually composed of from eight to 



sixteen free joints (PI. 12, figs. 26^2, 266, 272) and rarely with a differentiated 

 style or bristle; anal cell widely open, rarely narrowed in the margin of the 

 wing, discal cell usually absent, second vein often forked; calypter absent; 

 palpi usually elongate, hanging downward and comprising four or five joints; 



body very rarely with bristles. (NEMATOCERA.) 2 



Antennae usually three-jointed, the third joint however often complex (PI. 12, 

 fig. 283) or bearing a differentiated style (PI. 12, fig. 300) or arista (Pl. 12, 

 fig. 30l) ; anal cell distally narrowed or closed, sometimes very short or even 

 absent, discal cell usually present, second vein never furcate; palpi short, 

 projecting forward, never with more than two jomts. (BRACHYCERA.) . 17 



2. At least nine veins reach the margin of the wing, discal cell often present, second 



and fourth veins forked 3 



Less than nine veins terminate in the margin of the wing, no discal cell 9 



3. Costa continuing around the hind margin of the wing; ocelli almost always 



wanting 4 



Costa much thinned beyond the tip of the wing; a single pad between the tarsal 

 claws; ocelli present; males holoptic; wings usually spotted. (Rhyphus, 

 Olbiogaster) (PI. 12, figs. 276, 288) {ANISOPIDM, PHRYNEIDjE). 



RHYPHIDJE 



4. Veins bare or nearly so, if hairy the mesonotum has a V-shaped suture; legs 



very long and slender; body and wings elongate; males dichoptic, i. e. the 



eyes not meeting above 5 



Veins, including the hind margin, very hairy or scaly; body hairy or scaly; 

 mesonotum without a transverse suture 6 



