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THE SCOLYTID BEETLES. 

 SEASONAL HISTORY. 



OVERWINTERING STAGES. 



The winter is passed in the bark on trees attacked the previous 

 summer, as parent adults, larvae, and developed broods of young 

 adults. 



ACTIVITY OF OVERWINTERED BROODS. 



The spring activity of the overwintered broods appears to be similar 

 to that of species 9 and 10. It appears that the overwintered broods 

 begin to emerge from the dying trees toward the last of July, and to 

 enter the bark of other trees to excavate their galleries and deposit 

 eggs, but many, and perhaps the majority, of the overwintered broods 



Fig. 61. — The Jeffrey pine beetle: Distribution map. (Author's illustration.) 



do not emerge until after the middle of August. Some of the broods 

 of the first generation probably develop before cold weather, but it is 

 not likely that any of them emerge before the following July. 



HABITS. 



The habits of this beetle appear to be quite similar to those of the 

 mountain pine and Black Hills beetles. Therefore, while the details 

 of its seasonal history and habits remain to be worked out, enough is 

 known to show that it is a dangerous enemy of the Jeffrey and yellow 

 pine, and that it will in all probability attack other pines within its 

 range. Since the above was written the insect has been found to 

 be quite destructive to the Jeffrey and western yellow pine in northern 

 California. 



