THE CANADIAN ENTOMOLOGIST. 245 



Fire Wounds the Prime Cause of Serious Loss of Timber. 



In studying the forest conditions and the influences that contribute 

 to the destruction of timber, I have found that a sliglit injury to the base 

 of a tree by fire offers favourable conditions for the attack of insects, which 

 result in the final destruction of the valuable wood of the tree. The fire 

 burns and kills the bark at one side of the base of the tree, which in itself 

 might not be a serious matter, since subsequent growth would heal it 

 over, but it was found that these slight wounds are subsequently infested 

 by Ptinid, Scolytid and Calandrid beetles and their larvte ; also by 

 Cerambycid, Buprestid and Lepidopterous larvae, which by their boring 

 either convert the inner dead wood into a dry powder, or their mines 

 give entrance to a "dry rot " fungus*, so that another forest fire finds in 

 these extended wounds the conditions most favourable for a still further 

 extension of the injury. Thus, frequent fires in the same forest may, by 

 this process, burn entirely through the trunk of a large tree. 



It was also found that these fire wounds are almost invariably followed 

 by a decayed condition of the heartwood, which results finally in a hollow 

 trunk. Previous observations led me to believe that insects were largely 

 to blame for the destruction of the heartwood of living trees injured by 

 fire and other causes. I therefore had a number of wounded trees felled 

 on November 9th, 1895, and the trunks split open so that I could examine 

 the causes and effects. 



I found in nearly every tree thus examined that the rapid extension 

 of the decay was due largely to Cerambycid, Lymexylon and Brenthid 

 larvae which had entered from eggs deposited in the edges of the fire 

 wounds, and that brood after brood of these larvte, aided by wood-infest- 

 ing ants, had completely honeycombed the heartwood for a great distance 

 above the wound. Thus the valuable heartwood was completely de- 

 stroyed or rendered worthless. By persistent search I was fortunate 

 enough to find in the heart of a chestnut tree the imago of one of the 

 Cerambycid borers, where it had recently transformed within its pupa 

 case. It was located near the heart of the tree, and about four feet and 

 a half above the upper edge of the wound, and three feet above any 

 decayed wood. This beetle was identified for me through the kindness 

 of Mr. Howard, of the Division of Entomology, as Centrodera bicolor. 



On May 19th, 1896, I cut another example of this species from a 

 tulip log, at Pickens, W. Va., where I had previously discovered (June 



* Merulius lacriinaus. 



