LARVAL HABITS OF THE TIGER BEETLES. 



175 



will nearly all go through their transformations without^the winter rest and 

 emerge as adults in December or January. 



The adult beetles burrow into the ground for hibernation in the late 

 summer or early autumn. Individuals of C. repanda have been found con- 

 gregated in large numbers on sloping sandy surfaces in the middle of 

 October. Their hibernation burrows are about 30 cm. in depth, going in 

 obliquely for 15 cm. and then curving downward. The following depths were 

 recorded for individuals of the following species, taken from a loamy-=humus 

 bank : repanda, 5-10 cm. ; tranqueharica, 15 cm. ; purpurea, 10-12 cm. ; 

 duodecim guttata, 10-12 cm. Some of these were taken from the same 

 burrow, and one of the burrows was evidently that of a carabid. Griddle has 

 recently published an extensive paper describing the depth to which the 

 adults dig and the method of digging. 



The adults of species, e. g. JiirticoUis, which go into hibernation in early 

 September are not affected by being placed in a warm vivarium. Adults 

 which prepare for hibernation late in the autumn (purpurea, scutellaris, tran- 

 queharica, etc.) may be delayed by high temperature. In all cases where 

 high temperature continued, the individuals died in the soil or came out at 

 the end of a month or more and died soon after. 



It appears from these experiments that hibernation is a definite physio- 

 logical process so well impressed on the species, that extreme stimulation is 

 required to break it up. 



B. Temperature Relations. 



Under experimental conditions, the depth to which the larvae of C. purpurea 

 limbalis dig their burrows is related to the soil temperature (Table IV.) 



Table IV. 



