220 PSYCHODID.S. 



bristly or scale-like hairs in small groups or arcs on many of the 

 veins in many species. There are often small spots composed of 

 bristly or scale-like hairs, or of actual scales, occurring in various 

 parts of the wing, most frequently on or near the wing-border, 

 generally situated at the tips of the veins, or at the forking of the 

 veins. Flat, short, depressed, imbricating scales, cover parts of the 

 surface of the wing in some species ; rarely the whole surface 

 thus covered. Auxiliary vein short. 1st longitudinal vein ending 

 in the costa, generally beyond the middle of the wing ; 2nd longi- 

 tudinal forked near its base, the anterior branch again forked, 

 usually in the middle third of the wing. The 3rd vein arises 

 near the base of the 2nd, either before or beyond the forking 

 of that vein, and runs straight to the wing-tip. The 4th longi- 

 tudinal is forked, generally a little before or beyond the fork 

 of the anterior branch of the 2nd vein; the 5th, 6th and 7th 

 longitudinal veins normal, straight or gently curved. The 

 anterior cross-vein is always present, but is often difficult to 

 observe owing to its faintness in most of the species : it is 

 placed almost immediately after the base of the 3rd longitudinal 

 vein. Sometimes a distinct posterior cross-vein near the bases 

 of the 4th and 5th veins is discernible, the vein is therefore 

 presumably always present. A thick, long, uninterrupted fringe 

 around the whole wing-border, much more bristly or scale-like on 

 the costa, and often punctuated on both anterior and posterior 

 margins by small spots of snow-white or prismatic scales. Alulae 

 practically absent ; squamae (or tegulas) moderately developed or 

 small ; halteres distinct. 



Range. Probably world-wide, though no species are recorded 

 from Africa (except the Mediterranean Coast), Asia (except 

 India) and Australasia. 



Life-history. The perfect insects are commonly found in moist 

 situations, near streams, small drains or water-courses, in out- 

 houses and closets, very frequently on windows and in houses, 

 also generally distributed amongst low-growing vegetation. 



Table of Species. 



1. Membrane of wing wholly covered with 



closely placed imbricating scales apicalis, Brim., p. 223. 



Membrane of wing either without scales, or, 

 when present, the scales limited to a few 

 small tufts forming spots placed at the 

 tips of the veins : on the margin of the 

 wing ; or at the forking of the veins ; 

 never covering any appreciable extent of 

 the wiug-surface.* Sometimes a few, 

 irregularly placed, at the base of the 

 wings 2. 



* An apparent exception \sP.orbicularis, Brim., in which scales are present 

 on the basal portion of the veins only, but never on the membrane of the wing, 

 that is to say, emanating from the membrane. 



