June.^ipiS.] NiCOLAY & WeISS : BUPRESTIS IN NORTII AMERICA. 87 



Food plants, Piinis strohns, rigida and probably all the southern 

 yellow pines. 



Buprestis striata var. impedita Say, 36-160. 



canadensis Casey, 09-124. 



Identical in form and structure with preceding. Separated by dorsal 

 surface being more or less green with suture and sides of elytra cupreous, 

 pronotum and head green with bronze luster. Ventral surface and legs bright 

 green to bronzed cupreous. Length 13-17 mm. 



Records. — South Paris (Frost); Water ford; Cumberland County, 

 July 8 (Nicolay) ; Monmouth, June 23, ovipositing beneath chip pro- 

 truding from scarf of a white pine stump cut previous winter 

 (Frost) ; Maine. Sanborn, July 16; New Hampshire. Minnesota. 

 Essex County (Wiltbank) ; Bayshore, Long Island (Shoemaker); 

 Catskill Mts.; New York. Ft. Lee; New Jersey. Hummelstown, 

 April I, chopped from Pinus rigida log (Knull) ; State College, May 

 13 (Knull) ; Rockville, April 24 (Champlain) ; Pennsylvania. 

 Horn Mtn. Club (Sherman) ; Marquette, June 25, in wash up (Sher- 

 man) ; Michigan. Sudbury, Ont. ; Hymens, Ontario, Sept. i; 

 Canada. 



The fact that the variety occurs with the true striata prevents it 

 from being regarded as a good geographical race. In a large series 

 there are indistinguishable intermediates which prevent the raising of 

 impedita to specific rank. Impedita should be placed in collections as 

 a distinct color variety of striata but we believe the line should be 

 drawn here. In our experience this species is never met with in 

 numbers but Sherman has taken it quite commonly in wash up along 

 the shores of Lake Superior during June. 



Shelford in his work '' Color and Color Pattern Mechanism of 

 Tiger Beetles" (111. Biol. Mon., Vol. HI., No. 4) concludes that the 

 brilliant colors of the group are due to thin surface films of material 

 having the properties of metals. Prof. Michelson is inclined to at- 

 tribute differences in the colors to differences in the chemical con- 

 stitution of the film and color changes during ontogeny to changes in 

 chemical constitution but states that this would be difficult to demon- 

 strate on account of the minuteness of the film. In view of this, it is 

 extremely probable that buprestid colors and color changes are due 

 to similar causes. 



