308 PROCEEDlNOii OF THE NATIONAL MVt^EVM. vol.40. 



Prothorax black on dorsal surface, shading into oUve on sides and 

 coxae. Legs black, with bluish olive stripe on lower surface. 



Mesothorax and metathorax black on dorsal surfaces, shading into 

 olive on lower sides. Legs as in first i)air. 



Abdomen with dorsal surface black, shading below into olive on 

 segments 1 and 2, into j'-ellow on segments 3 to 7, and into olive on 

 segments 8 to 10. 



5. Female. — Melanistic. I have a single melanistic female (fig. 108), 

 which approaches the male coloration.* 



Labrum gray, with black line al)ove. Frons blue on vertical and 

 black on horizontal surface. Vertex black, except small round dis- 

 connected postocular spots and the blue stripe from eye to eye along 

 its anterior edge. Eyes black on upper one-fourth, green below. 



Prothorax with black band across anterior lobe. Middle lobe black 

 on dorsal surface. Posterior lobe black, except a large blue triangle 

 on each outer angle. Coxae blue, with black anterior spot. Legs 

 black, with bluish stripe on inner surface. 



Mesothorax and metathorax with sides and lower surface blue, 

 with very broad middorsal and humeral stripes which fuse along the 

 middle two-fourths of their length, leaving a pah of oval blue spots 

 near the antealar sinus, and below, a pair of lanceolate blue spots 

 next the mesostigmal laminae. Legs as in the pro thoracic legs. 



The abdomen has the distinctive female coloration described in 

 No. 1. 



The "adult coloration," No. 3 of C(?muk females, is a stage which is 

 rather transitory, as the delicate blues, pink, and yellow become early 

 obscured by black, which in the very old females may become slightly 

 pruinose. The females, which I reared, emerged into coloration No. 1 

 or No. 2, and died while still in that color, but in the field I have 

 taken very fresh appearing females of coloration No. 3. Because of 

 the difficulty always found in arranging a large series of fresh females 

 in a series according to the age of their coloration, I have wondered 

 if coloration No. 3 could also be a teneral and representing a second 

 form of coloration. All the aged females are black. No. 4. As this 

 species frequ(»ntly emerges in swarms the tenerals are at times very 

 numerous. However, the coloration which is ordinarily found is 

 black (No. 4). At any time in May or June, when this species is 

 most abundant, individuals in every stage of coloration can be taken. 



Within a few hours after death the delicate pink, blue, and yellow 

 fade, leaving the dried specimens gray or pale brownish. 



1 Since writing this I collected a second fcnialo of this coloration in the Sacramento Valley of California 

 and several others at Palo Alto. In these the 4 thoracic blue spots are similar to those of the male. 



