HIBERNATION IN THE POTATO BEETLE. 383 



The author desires to express his appreciation to Prof. C. E. 

 McClung, and other members of the Zoological Department of 

 the University of Pennsylvania, for generous aid and suggestions. 

 To Doctor J. H. Bodine he is deeply indebted for helpful criticism 

 during the progress of the work and for advising investigation 

 of this problem. 



MATERIAL AND METHODS. 



The adult potato beetle, Leptinotarsa decemlineata Say, used 

 exclusively in these investigations, was reared from eggs deposited 

 by overwintering adults. 



The methods adopted for different lines of investigation varied. 

 The type of cage for determining the effect of various food 

 plants consisted of ordinary six-inch flower pots filled with soil, 

 in the center of which was sunk 35x1 inch glass vial containing 

 water and fresh food plant. The covering to this cage was made 

 of mosquito wire in the form of a circular cage of a diameter to 

 fit snugly within the inner upper rim of the flower pot, and 

 varying in height from 12 to 18 inches. These cages were set in 

 troughs of soil in an outdoor breeding house. A more elaborate 

 cage consisted of a wooden framework (20x18x14 inches), 

 constructed of inch pine, enclosed with mosquito wire and set on 



FIG. i. Types of cages used in the food experiments. This figure shows two 

 types: (i) circular cages composed of flower pots sunk in the soil with mosquito 

 wire tops; (2) large oblong cages constructed of inch pine, covered with mosquito 

 wire and set on the surface of the soil. Foliage was kept fresh in the cages by 

 inserting them in vials of water. 



