204 long's second expedition. 



[305] from that species at once, by the nervures of the wings 

 being altogether destitute of colored margins. 



3. B. ALBA. — White; vertex and anterior feet above dusky. 



Inhabits Winnepeek river. 



Thorax slightly tinged with pale yellowish-brown; anterior 

 feet short, rather robust ; nervures upon and near the costal 

 margin dusky. 



Length of the body 9 about half an inch. 



This insect appears in immense numbers. They rise upon the 

 wing in the evening, and their short existence in the perfect 

 state appears to be terminated before sunrise. For a more parti- 

 cular account of this species, see the Narrative. 



ASCALAPHUS Fabr. 



A. 4-MACULATUS. — Wings with a white costal spot ; antennae 

 as long as the body ; tergum varied with black and testaceous ; 

 eyes with a suture. 



Inhabits Pennsylvania. 



Head and stethidium covered by long cinereous hair, the latter 

 part blackish, varied with pale testaceous ; labrum honey-yellow ; 

 antennae as long as the body, dull yellowish -b rown ; incisures 

 blackish, elavum oval, compressed, blackish with pale incisures ; 

 eyes large, prominent, in the middle divided by an impressed line; 

 wings hyaline with a milk-white reflexion, an opake snow-white 

 spot near the tip of the costal margin, nervures black ; tergum 

 testaceous, segments with a dorsal line and oblong spot each side, 

 black, terminal segments nearly all black; sides black, varied 

 with testaceous. 



Length to tip of wings one inch and a half. 

 [306] Like the cayennensis Fabr. this species has a white spot 

 on each wing, but the elavum of the antennae is not truncated. 

 The eyes are each bisected by an impressed line in the middle, 

 as in the macidatus Oliv. and all others of this genus. This 

 species was found by Mr. William W. Wood. 



HEMEROBIUS Latr. Lam. 



1. H. IRRORATUS. — Blackish ; thorax with three lines and 

 lateral margin yellowish ; wings hyaline with black spots. 

 Inhabits United States. 



