440 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lis 



wanting, especially on frons and genae; deep scrobal cavity; a few 

 species with prominent striae converging on clypeus from below eyes 

 and across lower part of face. 



Antenna with one ring joint; pedicle usually shorter than first 

 funicle joint; flagellum usually with five truncate segments followed 

 by sixth segment that is separated from the terminal unit of two 

 closely fused segments by a distinct annulation, but never as deeply 

 excised as the preceding five segments; flagellum usually filiform 

 although in a few species the terminal three units may be slightly 

 swollen or subclavate. 



Foretibia with a single curved tibial spur; hindtibia with two 

 straight tibial spurs, one slightly longer than the other; front coxa 

 rectangular with a shallow transverse depression on anterior surface; 

 depression may be outlined ventrally in a few species by a raised carina. 



Wings clear and hyaline; forewing with a short marginal vein that 

 may be longer than or equal in length to the postmarginal ; both veins 

 most often Imear, although in a few species marginal may be broader 

 than postmarginal and more heavily chitinized; no true stigma; 

 stigmal vein shorter than or equal in length to marginal and ending 

 in a small club; only other vein present is the submarginal. 



Male. — Smaller than the female, ranging from .85 to 4.2 mm. in 

 length. Resembles the female as far as head, thorax, legs, and wing 

 characteristics are concerned. Chief differences are in antenna and 

 abdomen. Antenna consists of a scape with a rounded, knoblike 

 protuberance just below articulation with petiole; flagellum mth 

 five, occasionally four, longer than wide, dorsally produced, pedicellate 

 segments with two long whorles of hairs on two, three, and four; 

 terminal unit of two or three closely fused segments. Abdomen with 

 an elongate petiole, equal to or longer than hindcoxae; shape of the 

 abdomen from the side triangular to oval; in cross section round to 

 oval and not as long or deep as in female; sixth tergum usually the 

 longest. 



Summary of generic characteristics (female only): Small; mostly 

 black with extremities of femur and tibia, often tegula, scape of 

 antenna, and tips of ventral valves yellow; abdomen with seven terga; 

 most often showing varying degrees of lateral compression; sixth 

 tergum usually as long or longer than fourth and fifth combined and 

 with fine scalelike sculpturing on at least lower lateral surface ; ninth 

 tergum often elongate and pointed, bearing a round cercus on each 

 side. 



Female genitalia with dorsal and ventral valves produced dorsally, 

 anteriorly, in varying degrees so that stylet arch may be in a horizontal, 

 oblique, or vertical plane. 



