THE CARPENTER ANT AS A DESTROYER OF SOUND 
WOOD* 
By S. A. GRAHAM 
The carpenter ant, Camponotus pennsylvanicus Degeer and its 
variety ferrugineus Fab. have been universally referred to in ento- 
mological literature as workers in decaying wood, but apparently never 
have been regarded as pests of sound trees or timbers. Wheeler’ men- 
tions the species repeatedly as a dweller in rotten and rotting wood but 
never as attacking sound material. Marlatt? states that “it normally 
constructs its galleries in logs and dead trees in the forests, but not in- 
frequently, in the case of wooden houses, and especially those near 
forested tracts, gains access through porch beams or the underpinning 
of such houses and mines and weakens the supporting timbers and 
other woodwork. As a rule, it affects only decaying portions of the 
wood, but sometimes carries its channels into the sound wood.” Com- 
stock® also refers to this species as working in rotten wood. 
Until recently the observations of the author have tended to con- 
firm the facts as set forth in literature, and so when reports were re- 
ceived stating that ants were responsible for a large amount of dam- 
age to standing white cedar in Minnesota, it was believed probable that 
this ant injury was only secondary to heart rot and that the ants were 
not primarily injurious. <A trip through the cedar districts of the state 
showed, however, that this assumption was erroneous and that car- 
penter ants were frequently found working in the solid heart wood of 
living white cedars, causing extensive injury. 
It seemed that this injury to living cedar has been regarded by the 
cedar dealers as a necessary evil and except for culling heavily ant in- 
jured poles, little thought has been given it. There has been no effort 
to reduce the loss occasioned by this pest on the part of the cedar 
men and perhaps for this reason the problem has never before come to 
the attention of entomologists. It is nevertheless an important prob- 
lem for the forest entomologist and will become more important with 
the increasing scarcity of white cedar of pole size. 
*Published with the approval of the Director as Paper No. 157 of the Journal 
Series of the Minnesota Agricultural Experiment Station. 
1 Wheeler—<Ants: Their Structure, Development and Behavior (1910). 
2 Marlatt—House Ants: Kinds and Methods of Control U. S. D. A. Farmers 
Bulletin 740 (1916). 
3 Comstock, A Manual for the Study of Insects (1907). 
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