THE PINE INVESTIGATION. 401 



the outer bark. The largest number of adults however, pass 

 the winter in the pupa cases. 



Food burrows. The preliminary galleries, may possibly be, 

 in some cases, excavated by the adults for the purpose of ob- 

 taining food, and the peculiar excavations at the terminus of the 

 brood galleries may be simply food burrows. No further evi- 

 dence of food burrows have been observed. 



LIFE HISTORY. 



The sudden disappearance of this species prevented a thor- 

 ough study of its life history, but enough was learned to enable 

 me to give a fairly complete outline of it. 



'Hibernation. The winter is passed in ail stages, both in the 

 inner and outer bark in which broods developed. The adults, 

 pupae and matured larvae in the pupa cases in outer corky 

 bark, the young larvae and eggs 1 in the inner bark, 



STAGES OF DEVELOPMENT. 



The egg. Tne exact time it takes the egg to hatch, iias not 

 been determined; but it is less than eight days and probably 

 not more than three or four, since in breeding experiments 1 

 found young larvae in eight days after the female had com- 

 menced to excavate her gallery. The larva, under normal con- 

 ditions, develops from the egg to pupa in from thirty to forty 

 days. 



Thepupa. The duration of the pupa stage has not been ac- 

 curately determined, but the evidence obtained indicates that 

 it is from ten to twelve days. The average duration of all 

 stages from egg to adult 1 have found from breeding experi- 

 ments and observations under natural conditions, to be from 

 forty to sixty-five days, and have concluded that under normal 

 conditions, the adult may develop and emerge in about sixty 

 days from the time the egg is deposited. 



NUMBER OF BROODS. 



The adults of the hibernating broods commence to emerge 



1. Eggs were observed November 7th and the following May. The latter in galleries 

 evidently excavated the previous fall. 



