EXPERIMENT STATION BULLETINS. 289 



head. The post scutellum is a mere line. The metathorax narrows slightly 

 behind. A sharp, black, central longitudinal ridge separates the meta- 

 thorax into two equal portions. Its posterior angles show a brush of stiff, 

 light-colored hairs. The wings are large, iridescent, and conspicuously 

 clouded, with three spots. The outer cloud is largest and densest and 

 extends back from the stigmal vein. The other clouded spots extend back- 

 ward from the angle, and from near the extremity of the sub-marginal vein. 

 A thick group of scale-like hairs mark the veins where the clouded spots 

 touch them. A clouded line behind the clouded spots runs nearly parallel 

 with the internal margin of the wing. The costal cell is distinct, and is sym- 

 metrically divided by cross scales. The sub-marginal vein is about twice as 

 long as the marginal The post-marginal and stigmal are rather short, the 

 former being the longer. A portion of the posterior margin of the wing is 

 quite thickened so as to resemble a vein. The outer margin and internal 

 angle are fringed with short hairs. The secondary wings are clear and 

 beautifully iridescent, broad lines of different colors running lengthwise of 

 the wings, and these are cut across with diagonal striae. The sub-marginal 

 vein reaches to the middle of the wing. The costal cell is fringed at its middle 

 with hairs, as is the whole internal margin of the wings. The legs are dark 

 along the front, and brownish behind. The anterior coxa? are dark blue 

 with a purple reflection; the anterior femora are greBn and very large. A 

 deep groove marks these large femora on the inner side to receive the 

 tibia?. One margin of this groove is finely serrate. All the coxa? are 

 large. One tibial spur marks the anterior and posterior legs, and two the 

 middle. The tibia? are margined with stiff hairs. First joint of tarsi, long, 

 white, the three following equal and all together as long as the first. The 

 second to the fifth joints inclusive are white, except the tips of the fourth 

 and fifth which are dusky; claws dark. 



The abdomen is petioled, broadened posteriorly, and about as wide as 

 the metathorax. First joint is narrow and brownish yellow, the second 

 broader, blue black, tipped with yellow. The remaining joints are dark 

 blue. The fourth and fifth joints are broadest and longest. The insect is 

 dark blue beneath, except the prothorax and petiole of the abdomen, which 

 are yellowish brown. Length, five mm. Described from two specimens. 



The female differs from male in size, the antenna?, prothorax, wings, 

 and abdomen. The antenna? are much shorter, reaching only to the meso- 

 thorax, and are more clavate. The joints are the same in number — thir- 

 teen — but the separate joints are shorter. The prothorax is a little smaller, 

 broader at the ridge, and a little less roof-like. The wings are less 

 clouded; the two inner spots are very obscure or wholly wanting. The 

 abdomen is almost sessile, nearly oblong, and gradually narrowed at the 

 base. The first joint is yellow, the remaining six joints blue-black. 

 Length, four mm. Described from many specimens. 



We wish to acknowledge valuable assistance rendered by Dr. C. V. 

 Riley, Prof. L. O. Howaed, and also to Mr. F. J. Niswander who made 

 part of the drawings. 



A. J. COOK. 

 G. C. DAVIS. 



37 



