AMERICAN DIPTERA. 



273 



On account of the rarely fuscous base of the abdomen, this spe- 

 cies may become confused with basalis Loew, from which it may be 

 readily distinguished by the brownish thoracic bristles. 



This species, together with nugax sp. nov., is the Hilara men- 

 tioned by Mr. Wheeler in his paper on "Anemotropisra and other 

 Tropisms in Insects, p. 375,"* as dancing in swarms. 



Hilara nngax sp. uov. 

 This species differs from congregaria as follows : 



Male.— Thoracic and cephalic bristles slightly longer and stouter, darker, 

 piceous or black. Antennal style more slender. Palpi piceous, with darker 

 hairs. Hypopygial lamellae not serrated. Legs darker testaceous, piceous or 

 black from the middle of the tibite ; anterior metatarsi without long hairs above, 

 underside straight. Halteres fuscous. Wings cinereous hyaline ; veins darker 

 fuscous, stigma dark fuscous. 



i^ema/e.— Differs from the male thus: legs lighter in color, tibia? with more red- 

 dish, metatarsi not incrassate. The hind tibise of the female are not at all thick- 

 ened. 



Twenty nine males and twenty-four females; Monterey Co., Cali- 

 fornia, July 3 to 23, 1896. Collected by Dr. Wheeler. 



HORMOPEZA Zetterstedt. 



Rather small species. Antennae much shorter than the head, 

 apparently two-jointed, the terminal joint ovate, compressed, with 

 a short, thick end- bristle. Eyes of the male contiguous above. 

 Hypopygium of the male rounded, consisting of two convex, shin- 

 ing, hemispherical plates, between which reaches a short hairy pro- 

 cess. Legs simple. Wings as in Hilara. 



The species are distinguished from Hilara by the contiguous eyes 

 of the males, the simple metatarsi of the males, and by the structure 

 of the an ten use. 



Stigma and veins fuscous; third antennal joint oval ; knob of halteres blackish. 



nigricans Loew. 



No stigma, veins pale • -2. 



2. Third antennal joint oval ; halteres and legs luteous builata sp. nov. 



Third antennal joint globose ; halteres and legs fuscous. 



brevicornis Loew. 



Hormopeza brevicornis Loew (Fig. 87). 

 Cent, v, 65. 



Head black, eyes of the male contiguous. Front shining above the antennae. 



* Archiv fuer Entwickelungsmechanik der Organismen. 8th Band, 3rd Heft. 

 1899. 



TRANS. AM. ENT. SOC, XXVIII. (35) AUGUST, 1902. 



