5 
a later letter he says: “The elm trees, not only in this city, where 
they have been our chief shade tree, but in the surrounding coun¬ 
try, are dying from some disease that is a mystery to our people. 
There is apparently no disease of the leaf—no web formed—but 
the leaves begin to dry up and to die, and finally, in a few months, 
the tree is dead. A number of the finest shade trees in the city 
have gone that way. There are many that now show evidences of 
the disease.” 
In consecjuence of this information I sent to Fairfield in the 
fall of 1907 Mr. H. E. Hodgkiss, an entomological assistant in my 
office at the time. As the primary cause of the disease seemed a 
matter of doubt, and might possibly be a fungous infection, or 
even cultural conditions merely, Mr. Hodgkiss was accompanied on 
his trip by Professor T. J. Burrill, of the University of Illinois, 
who kindly consented to assist us in the solution of the problem. 
After a thoro examination of several dead and dying trees in and 
about Fairfield these gentlemen came to the conclusion that the 
cause was a complex one, but differed in judgment as to the pri¬ 
mary factor, Professor Burrill believing it to be the round-headed 
borer of the elm (Sapcrda tridentata, Fig. 1), which was abundant 
under the bark of most of the injured trees, and Mr. Hodgkiss 
concluding, on the other hand, that the original difficulty was in 
the roots. 
Causes oe the Injury 
The condition of the roots described above by Mr. Smith and 
a general infestation of the trunk and larger branches by borers, 
are found together at the same time and place, and usually in the 
same trees. The well-known disposition of the borers generally, 
and especially of the elm-tree borer, to infest first and most freely 
trees already suffering from some other cause, adds to our uncer¬ 
tainty concerning the share which these two causes may take in the 
destruction of our elms. It is probable that sometimes one is pri¬ 
mary, and sometimes the other. The root injury may come to a 
tree already infested by borers, or the borers may come to infest a 
tree already affected at the roots, each injury intensifying the 
other, and both together destroying trees which might survive 
either alone. Even elm trees in the forest are more or less infested 
by the round-headed borer and other insects of similar habit. Mr. 
Flint reports, for example, that in his inspection of woodlands, he 
found this borer abundant in dying trees thruout the state, and 
the larva of the elm curculio (Magdalis arniicollis, Fig. 3, 4) even 
more abundant in the northern counties. Small bark-beetles were 
