February, '10] severin : SAN JOSE SCALE 103 



inspector; the heavy, black dots show the localities in which my 

 brother and I have found this pest. 



From the present data on the distribution of the San Jose scale in 

 Wisconsin, it is apparent that it has not been found in the transition 

 zone as limited by the earlier map; however, according to the later 

 corrected map, the pest has established itself within this zone. As 

 Marlatt^ writes, "too much stress, however, should not be put on 

 zonal limitations, and there may always be outbreaks of longer or 

 shorter standing in the borders of the transition region." 



While collecting insects in the vicinity of Madison no attention 

 was at first paid to ascertaining the presence of scale insects, but 

 while working at Tenny Park, which is located about three or four 

 miles northeast of the State Experiment Station, my attention was 

 drawn to a very serious infestation of the Willow scale, Chionaspis 

 salicis-nigrce (Walsh).* It occurred most abundantly on two species 

 of dog- wood; the red dog- wood, Cornus stolonif era, and the gray 

 dog-wood, Cornus paniculata. So serious was the infestation that on 

 many of the red dog-wood shrubs not a bit of red bark was visible, 

 the twigs and branches being plastered from the very tips of the 

 twigs to the roots with this conspicuous white scale. On the red dog- 

 wood these were accompanied by a very serious infestation of the 

 San Jose scale, causing the shrubs to appear as if covered by soot from 

 the nearby factories and railroads, leaving only here and there small 

 patches of red bark on the branches. In Vilas Park and in a cemetery, 

 both within two miles of the State Experiment Station, the San 

 Jose scale was again found upon recently planted shrubs. 



A twig of this material, which was collected in Tenny Park, was 

 sent to Mr. J. G. Sanders, agent and expert at the Bureau of Entomol- 

 ogy, Washington, D. C, in order to have him verify my identification. 

 In a letter he writes: "Your letter of November 7, and accompany- 

 ing specimen of scale at hand. You were correct in your determina- 

 tion of this scale insect as the genuine San Jose {Aspidiotus per- 

 niciosus Comst.). The twig which you sent was very seriously in- 

 fected, indicating that this particular tree had been infested for at 

 least two or three years." 



* Prof. Wm. S. Marshall has pointed out to me, along the University Drive 

 in Madison, this same scale insect, which has become so injuriously abundant 

 on the American Aspen or Quaking Asp (Populus tremuloides) as to kill some 

 of the trees. 



