66 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 reddish or 

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

 the white bark of the trunk and larger branches at the point where the insect 

 is preparing to hibernate and transform in the wood beneath. 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 indicates 

 its presence in the above described characteristic and sometimes conspicuous 

 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 white birches is a small, slender, olive-bronze colored 

 beetle nearly half an inch in length (7.5-11.5 m m.), as shown in Figs. 31 

 and 35. * Its general color and the fact that it works mostly in birch trees 

 suggested the good popular name of Bronze Birch Borer for the insect. How- 

 ever, 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. 



*Chittenden (Bull. 18, U. S. Div. of Entomology, p. 47) technically describes it as 

 of moderately robust form, subopaque, olivaceous bronze in color. The last ventral 

 segment is oval at the apex ; the punctuation of the prothorax is transversely strigoso 

 punctate, and its posterior angles are carinate in both sexes ; the first ventral segment in 

 the male is broadly grooved ; the second more deeply, the groove being narrow and smooth 

 (see t in Fig. 31). The serration of the antennal joints begins with the fourth joint. The 

 elytra bear each a rather vague longitudinal costa and the scutellum is transversely 

 carinate". The popular name of the insect was first suggested in this account by 

 Chittenden. 



