THE MONTHLY BULLETIN. 



151 



This small biiprestid beetle must not be blamed, however, for all of 

 the foliage that is destroyed upon our oaks, for there are a number of 

 insects and fungi that have as a host plant this tree. There is one 

 patliologieal trouble of -which little seems to be knowni which kills the 

 smaller braiu'hes and leaves in such a way as to greatly resemble those 

 killed l)y the twig girdler. and is quite liable to cause confusion in 

 establishing the identity of the disease in question. There is, neverthe- 

 less, a superficial distinguishing character that enables one to differen- 

 tiate these two diseases at a glance, and this is found in the coloration 



Fig. 54. — Small twis of the live oak showing the charac- 

 teri.stic injury of the twig girdler. The corky bark covering 

 has been removed above the burrow. (Original.) 



of the dead leaves. The foliage that has died as a result of beetle work, 

 appears, when thoroughly dry. a light straw color, while those that have 

 been killed as a result of a fungous attack in the branches below, possess 

 a distinctive reddish-brown tinge. These characteristic qualities have 

 been found to be quite reliable in the Santa Clara Valley, where most of 

 the observations relative to the life-habits of Agrilus politus were noted. 

 Observations have not been made in any other region than that cited, 



