140 Bulletin 234. 



Indications of the Insect's Presence 



The presence of this insect in birch trees is not easily determined until 

 it has been at work for a year or more. The first intimation one usually 

 has of its presence is the dying of some of the top branches of the tree. 

 This is well shown in the frontispiece and in Fig. 34. This dying of the 

 tops of the trees has been very characteristic of the work of this pest 

 wherever I have seen it in New York. The whole tree often succumbs in 

 another year or two. Rarely the trees might begin to die at the top from 

 a condition known as '' stag head " caused by lack of moisture and food 

 materials. A careful examination should readily locate the borer if it is 

 the culprit. Some have tried to save a tree by pruning out the dead branches 

 or top, but without avail, for by that time the whole tree usually is infested. 



Sometimes one can determine in autumn whether a tree is infested by 

 this insect, even before any branches have been killed. Characteristic red- 

 dish or rusty brown spots or discolorations, as shown at a in Fig. 30, often 

 occur on the wdiite bark of the trunk and larger branches at the point 

 wdiere the insect is preparing to hibernate and transform in the wood be- 

 neath. Usually the insect can be easily located by cutting through the 

 bark and into the wood beneath these rather conspicuous spots. 



Another peculiarity which characterizes the work of the insect is the 

 ridge which often develops in the bark over the burrow on the branches, 

 as shown at b in Fig. 30. 



Thus, while the insect works in rather an obscure manner, it indi- 

 cates its presence in the above described characteristic and sometimes con- 

 spicuous ways. Unfortunately, however, it is usually then too late to save 

 the tree, but much can be done to prevent further infestation of other trees. 



Characteristics of the Enemy 

 This destroyer of wdiite birches is a small, slender, olive-bronze 

 colored beetle nearly half an inch in length (7.5— 11. 5 mm.), as shown in 

 Figs. 31 and 35. -'Tts general color and the fact that it works mostly in 

 birch trees suggested the good popular name of Bronze Birch Borer for 

 \\\Q insect. However, it is not in this adult or beetle stage that the insect 

 is destructive. It is injurious only during its life as a larva or grub when 

 it is a borer. 



*Chittcnden (Bull. i8, U. S. Div. of Entomolop:>', p. 47) technically describes it 

 as " of moderately robust form, subopaquc, olivaceous bronze in color. The last 

 ventral segment is oval at the apc.x ; the punctuation of the prothorax is transversely 

 strigoso-punctate, and its posterior angles are carinatc in both sexes ; the first 

 ventral segment in the male is broadly grooved ; the second more deeply, the groove 

 being narrow and smooth (see b in Fig. 31). The serration of the antennal joints 

 begins with the fourth joint. The elytra bear each a rather vague longitudinal costa 

 and tlie scutellum is transversely carinate." The popular name of the insect was 

 first suggested in this account by Chittenden. 



