THE PINE INVESTIGATION. 375 



fested trees, but the bodies of the dead specimens were not 

 covered by the white substance. This was thought at the time, 

 to be due to some unfavorable conditions of the infested bark, 

 and was not carefully studied Subsequent observations lead 

 me to believe that this was also due to a disease ; either an un- 

 recognized form or stage of the new fungus determined by 

 Prof. Peck, or was most likely caused by an entirely different 

 fungus or bacterium. 



These two characteristic conditions were occasionally met with 

 in 1892, in all of the regions of the State in which I conducted 

 investigations, except in the spruce where nothing but the 

 adult and egg stages were observed, 1 and here many of the 

 adults were dead in their bark galleries, some surrounded by 

 the white substance, while others were not. 



It would appear, therefore, that one or more kind of diseases 

 were quite thoroughly distributed over the infested area, and 

 that the insect had commenced to die, and many individuals of 

 the species had perished, before cold weather set, in in Decem- 

 ber, 1892. In fact the diseases (if diseases were the cause of 

 the extermination of the species) must have assumed by this 

 time, sufficient proportions to have infested all, or nearly all 

 living examples before they ceased work and became dormant. 

 If so. the first warm, sultry days of spring following a severe 

 winter would have offered the most favorable conditions for 

 the rapid development of the disease or diseases into an epi- 

 demic, which might soon exterminate the species in all of the 

 area within its range. The conditions found in the spring of 

 1893 would indicate that this might have been the case. As 

 previously stated, dead examples of the insect in all stages 

 were found in great numbers in all of the infested trees that 

 were examined during April, May and June, 1893. 



The dead larvae and pupae had every appearance of insects 

 that had died from a bracterium disease. Most of them found in 

 April and May had turned black and were in an advanced stage 

 of decay; the internal structure having been converted into a 



1. Subsequently, bark was taken from dead spruce trees showing the larval galleries 

 and pupa chambers of the species, 



