February, ’18] wilson and gentner: cabbage worm 
79 
tions before and after spraying in the field, than in the tests is easily 
explainable by the fact that the beetles had recently emerged when the 
collections were made, and were feeding indiscriminately. The 
seasonal life history of Diabrotica vittata must be kept in mind in inter¬ 
preting all of these tests. 
It is evident, as has been mentioned by others, that Diabrotica 
vittata is difficult to poison. In cases where Bordeaux mixture is of 
value in controlling plant diseases, it may be used to advantage with 
lead arsenate or preferably zinc arsenite. Under conditions which 
prevail in the cucumber growing sections of the North Central States, 
its value as a control of the striped cucumber beetle does not warrant 
the expense of application. 
President R. A. Cooley: Do you wish to discuss this interesting 
and valuable paper? If not, we will pass to the next paper, “The 
Imported Cabbage Worm in Wisconsin,” by Mr. Wilson and Mr. 
Gentner, of Madison, Wis. 
THE IMPORTED CABBAGE WORM IN WISCONSIN 
By H. F. Wilson and L. G. Gentner, 
University of Wisconsin , Madison , Wis. 
There is a general belief among Wisconsin canners and growers that 
it is dangerous to use cabbage that has been sprayed with poisons of 
any kind. Both canners and growers recognize the fact that the cab¬ 
bage worm is a serious pest but the growers have not been free to use 
essential combative measures because they consisted of spraying with 
arsenicals. 
Other investigators have already shown that cabbage sprayed with 
arsenicals may be eaten without danger to the consumer but in order 
to more thoroughly convince Wisconsin growers of these facts, the in¬ 
vestigations from which the included data was secured were planned. 
The life-history work of two seasons has shown that there are three 
distinct generations each year and sometimes a partial fourth. There 
is normally more or less overlapping of generations, especially toward 
the latter part of the season. The maximum emergence of adults 
from overwintering chrysalids occurs somewhere from the first to the 
middle of May, depending upon the season. The maximum emer¬ 
gence of adults of the first generation occurs during the first two weeks 
of July; and of the second generation during the first two weeks of 
August. 
