NORTH AMERICAN BUPRESTID BEETLES 217 



times there are four vague depressions on the front, and a feeble, 

 longitudinal groove on the occiput; and the prosternal lobe is 

 broadly emarginate or subtruncate in front. In some examples the 

 pronotum is widest at the middle, with the sides arcuately rounded, 

 whereas in others it is widest at the apical third, and more obliquely 

 narrowed posteriorly, the depressions are variable in depth, and occa- 

 sionally the prehumeral carinae are obsolete. Length 4.75 to 8.5 

 millimeters. The male genitalia are similar in all of the forms 

 examined. 



In a large series of adults from Montana the greater number have 

 the elytra uniformly pubescent, whereas in a series reared from maple 

 in Colorado nearly all of the specimens have the elytra practically 

 glabrous. In a very large series reared from willow in California 

 the elytra are either pubescent or glabrous, with all forms of inter- 

 grades. In a series of 36 specimens collected by G. A. Harding on 

 willow during May and June, on Vancouver Island, all were of a 

 dark color (none reddish or cupreous), mostly steel blue, with a few 

 olivaceous green or nearly black examples, and the* elytra without 

 distinct pubescence. 



Hosts. — This species has been reared from dwarf maple {Acer 

 glabrum Torrey), striped maple {Acer pennsylvanicwn Linnaeus), 

 white or arroyo willow {Salix lasiolepis Bentham), mountain or 

 Nuttall willow {Salix scouberiana Barratt), weeping willow {Salix 

 babylonica Linnaeus), Western black willow {Salix lasiandra Ben- 

 tham), and probably will attack all species of willow. It has' also 

 been recorded as having been reared from other host plants, but 

 these records are probably from erroneously identified specimens. 



The type of cupreolus {politus No. 11) in the LeConte collection is 

 a female, 9 millimeters in length, and is of a uniform bronzy cupre- 

 ous color, with a slight reddish tinge, and rather densely, uniformly 

 clothed above and beneath with whitish hairs. The type of plumbeus 

 {politus No. 16) in the LeConte collection is also a female, measuring 

 7 millimeters in length, the head and pronotum are dark brown, with 

 a feeble purplish reflection, the elytra are slate colored with a vague 

 greenish tinge, moderately shining, and uniformly clothed with 

 white pubescence similar to cupreolus. The type of desertus {politus 

 No. 23) in the same collection is also a female, 5.75 millimeters in 

 length, above bronzy brown, with a distinct purplish or cupreous 

 tinge, sparsely clothed with white pubescence, but not so densely as 

 in either cupreolus or plumbeus, and the body beneath is densely 

 clothed with long, white pubescence, which does not obscure the sur- 

 face. The name desertus was previously used by King for a species 

 of this genus from Arabia, so Harold (1869) renamed it solitarius. 

 Doctor Obenberger has kindly sent me a paratype of his canadensis 



