370 Kelation of Watek to the Behaviok of 



which took place under adverse circumstances in the early fall of 1912, were of 

 the induced type. At Tucson Station B this behavior was not discovered in 

 either the winter generation of 1911 or that of 1912, since the environmental 

 conditions always produced desiccation in the early fall at this locality, thus 

 causing the beetles to be in hibernation about 10 months each year ; they emerged 

 about the middle of July, and after feeding for a short period re-entered hiber- 

 nation late in August. At the Chicago Station, however, normal hibernation 

 always occurred, because the environment was normal, for no excessive desicca- 

 tion or any other climatic adversities appeared. It became necessary, therefore, 

 to determine if these results could be confirmed by further data, so the following 

 hibernation tests were carried out. 



For these tests 30 emerging adults (Tucson A, g. II) on September 2 were 

 placed in a hibernating pedigree-cage containing potato plants for food; the 

 soil was a mixture of equal parts of sand and adobe, and water was added twice 

 daily, but the plants completely filled the cage. The experimental conditions, 

 therefore, were apparently normal throughout the test. It was discovered by 

 daily observations that these animals were in hibernation on September 18 and 

 when dug up on October 2, the first adults were uncovered at a depth of 20 cm., 

 but the larger number of beetles were found at the bottom of the pot. The 

 beetles were inactive when first removed, but began to move in a few minutes at 

 an air-temperature of 33° C. Various tests in the field demonstrated that they 

 possessed no reactions to food or dry soil, but within 5 minutes they did respond, 

 and all burrowed into the moist earth at a temperature of 21° C. This indicated 

 that a cool moist soil accelerated the entrance reaction. These results were 

 further tested to determine if similar reactions always took place. 



On September 2, 130 emerging adults (Tucson A, g. II) were put into a 

 hibernating cage, which had been previously filled with potato plants, and in 

 which the soil consisted of a mixture of equal parts of adobe and sand, to which 

 water was added twice daily; thus the conditions were approximately normal, 

 for no desiccation occurred. The beetles responded to this set of conditions, 

 for they were in hibernation by September 22. When dug up on October 21 

 the insects were found distributed through the soil from the top to the bottom 

 of the cage, but when tested in the field showed no reaction to food or dry soil, 

 and when brought into contact with cool moist soil, out-of-doors, they burrowed 

 into it within 5 minutes. 



This activity was again tested in the following manner: 51 emerging adults 

 (Tucson A, g. II) were removed September 3 and were placed in a hibernating 

 cage filled with Solanum hertwigii for food. In this experiment a different 

 food plant was also used, but with no apparent result upon their behavior. The 

 soil was also of equal parts of sand and adobe, and water was added each morning 

 and evening, so that the experimental conditions were apparently normal. All 

 the animals were in hibernation by September 19, but when dug up on October 3 

 only 46 adults were alive. The first individuals, however, were discovered at 

 a depth of 29 cm., and the majority were at the bottom of the pot. When 

 tested in the field no reactions to food or dry soil were observed, but when 

 brought into direct contact with cool moist earth all burrowed into it imme- 

 diately. Thus when normally hibernating beetles of the winter generation were 

 removed from hibernation a cool moist soil was necessary to initiate this 

 behavior. 



