112 
ARTICLE VII. INSECTS INJURIOUS TO THE ELM. 
1. The Elm Borer, (Saperda tridentata, Oliv.) 
Order Coleoptera. Family Cerambycid^l 
(Plate XII. Fig 2.) 
For several years past my attention has been attracted by 
gradual decay and death of the rows of white elms (Ulmus america 
in the towns of Normal, Bloomington, and Champaign. The diffici 
with the trees commonly commences, to declare itself from the n 
die of summer to autumn, when the leaves, first upon the termi 
twigs and then upon the larger branches, are seen to stop tl 
growth, change their color, and ultimately to fall. This loss is r 
urally followed speedily by the death of the branches themseh 
as is clearly evident the following spring, when these remain bl 
and lifeless while the rest of the tree is putting on its folia 
Usually the higher branches of the tree are those first affected, 
the whole top soon seems to blight, and in a year or two the i 
perishes utterly. This difficulty, commencing here and there, extei 
slowly from tree to tree along the rows, finally inevitably destroy 
every tree of this species in the immediate vicinity. 
In the autumn of 1888, I directed an assistant, Mr. Webster 
dig up a tree which had nearly died in this manner during 
summer, and to carefully examine the larger roots, the trunk, 
all the branches, with a view to ascertaining, if practicable, 
cause of the difficulty. The roots were found unaffected, but 
peeling the bark from the trunk, about half-grown larvae of Sapc 
tridentata appeared in considerable numbers in the still living p; 
of the w T ood, and those of Magdalis armicollis (Plate XI. Fig. 
were abundant where the bark and wood were already dead, 
manner in which the bark had been mined and burrowed by 
Saperdas, gave sufficient evidence of the cause of the death of 
tree, the borers having again and again completely girdled the tri 
Both the trunk and branches of this tree were cut up in lenj 
and boxed for the purpose of determining the details of the 
history of the species. The specimens were boxed Aug. 8, 
cracks of the boxes being closed by pasting over them strip 
paper, and each having left a glass covered opening in the top 
which it was assumed that the insects emerging would be attrac 
Later, this cover was removed, and a glass jar was inverted < 
the opening. 
