June, iSgo.] WeBSTER : NORTH AMERICAN SpECIES OF DiABROTICA. 67 



THE PROBABLE ORIGIN AND DIFFUSION OF 



NORTH AMERICAN SPECIES OF THE 



GENUS DIABROTICA.— II. 



By F. M. Webster. 

 / 



Since the publication of my paper in No. 4, Vol. Ill, of the Jour- 

 nal, a considerable amount of information relative to the subject has 

 since either been communicated to me, or placed at my disposal where I 

 did not before feel at liberty to use in print. I have, therefore, thought 

 best to add this supplementary note, including in it a few correc- 

 tions. 



Professor Cockerell has very kindly prepared the following table 

 illustrating the position of his D. vittata var. incerta, Ckll. found 

 by him from Mesilla Valley southward to Juarez, Mexico, opposite El 

 Paso, Texas, on the Rio Grande : 



A. Antennce with the three basal joint pale. 



a. " Legs yellow, the knees, anterior tihic^ and tarsi, and the tips of the middle 

 and posterior tibi^ and their tarsi, piceous." (Horn). vittata Fab. 



b. Legs more or less darkened, but basal third of anterior femora, and basal 

 two-thirds of middle and posterior femora, and hind tibia; more or less in mid- 

 dle, yellow. vittata var. incerta Ckll. 



B. Antennre all black. Legs all black except bases of femora, trivittata Mann. 



In regard to the distribution of these in the valley of the Rio 

 Grande, Prof. Cockerell gives me the following table : 



[Santa Fe, D. iz-punctata, (i specimen not taken by himself). 



i Gallinas Canon, D. atripeiniis, (reported by the Snow party). 



*5,0OO " Albuquerque, -i D. longicornis. 



*5,ooo " Socorro, I D. 12-punctata, . . D. leiimiscata. Collected by Prof. 



3,000 " Mesilla Valley, J Wickham, at Alberquerque. 



,, . ) Z>. tricincta. 



*3, " Juarez, Mexico, - „ . 



\ D. vittata var. incerta. 



The occurrence at Gallinas Cafion should have been credited to 

 Prof. Snow and not to Prof. Cockerell. Prof. Wickham calls my at- 

 tention to the fact of Dr. Horn's having observed a close resemblance 

 between Andrector d-pimctataYioxw, and Dlabrotica 12-pitnctata Oliv., 

 while he had himself confused a second species of Andrector with 

 Dlabrotica tricincta Say, and placed them in his collection as all be- 



* These records of elevations are supplied by myself and taken from surveys 

 made by the U. S. Geological Survey and published in 1S90. The elevation of 

 Juarez, Mex., opposite El Paso, Tex., is but little less than 3,800 ft. 



