INVESTIGATION OF LIFE HISTORY. 



49 



dormant condition. The specimens that were under observation 

 that year could not be expected to behave in a normal manner, 

 because they were received about July 20, and were collected possibly 

 three weeks before, so that they were deprived of food during the 

 height of the feeding season. 



They went into hibernation from August 12 to September 16, 1907, 

 although some would probably have entered earlier if a large supply 

 of food had not been offered them. 



This species always burrows into the ground to spend the winter, 

 unless the soil is so hard that this is impossible. Occasional specimens 

 may remain beneath leaves or moM in wooded areas, but we have no 

 data to show that this habit is normal, as is the case with some of the 

 species of Carabus. The hibernation cages used have been supplied 

 with earth which was rather loose and offered an excellent oppor- 

 tunity for the insects to burrow. 



The cavities range from 2 to 15 inches, but some have been found 

 20 inches below the surface of the ground. Calosoma beetles seldom go 

 below the frost line. They remain in these cavities until warm weather, 

 when they come to the surface of the ground in search of food. 



The weather has a most important bearing on the emergence in the 

 spring, but in general it may be said that Calosoma beetles will seldom 

 be found before June 1, which is a week or more after most of the 

 gipsy moth larvae have hatched. 



Table VIII shows the average dates of entering hibernation. 



Table VIII. — Average dates of entering hibernation by Calosoma sycophanta. 





Number of beetles. 



Age of 

 beetles. 



Average 

 date 

 males 

 entered 

 hiberna- 

 tion. 



Average 

 date 



Year. 



Males. 



Females. 



females 

 entered 

 hiber- 

 nation. 





/ 11 



ii 



Old 



Aug. 17 

 July 14 

 Aug. 8 

 Aug. 1 



Aug. 15 

 July 16 

 Aug. 5 

 July 31 



1908 



1909 



\ 12 14 

 103 83 



Young 



Old 



1910 



38 



39 



do 



This table indicates that the males and females enter hibernation 

 at practically the same date; while there is considerable variation in 

 different years, the average is about August 1 . 



The date when the beetles went into hibernation in 1907 was much 

 later than normal, as the specimens were not received from Europe 

 until late in July and were given a liberal supply of food. The record 

 of beetles for the next year is more nearly correct, as the only ones 

 included were those that had been used in reproduction operations dur- 

 ing the season. Old beetles are those that have entered hibernation for 

 the second time, while young beetles are those that pass through 

 100834°— Bui. 101—11 4 



