Our title does not refer to the six-footers who slash trees with axes and pruning-hooks, but to the small foes known as insects. The elm is injured by a number of such villains. All kinds of trees have insect enemies whose natural habit is to eat some part of the tree. Occasionally we hear of a tree which no insects will attack. The belief that such trees exist is based on incomplete study of those trees.
Wellhouse, W. H.
"Some Six-Footed Villians and The Elm,"
Ames Forester: Vol. 11
, Article 14.
Available at: https://lib.dr.iastate.edu/amesforester/vol11/iss1/14