RELATION OF INSECTS TO DEATH OF CHESTNUT TREES 223 



growth they transform to the adult stage in the outer wood, or hark, to 

 emerge the following spring and repeat the process. Our investigations have 

 shown that this is the most destructive insect enemy of the chestnut and 

 oak, and that it can be controlled by disposing of the infested trees in such 

 a manner as to destroy the bark on the main trunks during the fall and 

 winter months. 



INSECTS AND THE BLKJHT DISEASE 



Investigations by the Forest Pathologist of the U. S. Department of 

 Agriculture have made available much of the essential information relating 

 to the character of the organism which is responsible for this new disease 

 and how it kills the trees. They have found that the spores find their way 

 to the living tissue through some sort of wound or opening in the bark of 

 the trunk, branches, and twigs, and that the majority of such openings 

 appear to be caused by bark-boring insects. It has been stated by the Forest 

 Pathologist that in many parts of the country where the disease is prev- 

 alent 90 per cent of the infection by the chestnut blight disease is due to 

 a primary wound in the living bark made by bark-borers. Recent investiga- 

 tions by Mr. Craighead in Pennsylvania and examination of specimens sub- 

 mitted to us by the Forest Pathologist at Washington tend to verify this 

 general statement. It is found that a large number of species of insects are 

 more or less responsible for making a primary wound through which the 

 spores of the disease may find entrance to the living tissue and thus result 

 in a weakened condition or death of the tree which in turn contributes to 

 the multiplication and spread of both the disease and the interrelated insects. 



It is, therefore, evident that we have an insect problem of perhaps equal 

 importance to that of the blight itself. The Forest Entomologist as well 

 as the Forest Pathologist has more work to do before we can arrive at 

 definite conclusions as to the most economical and effectual methods of 

 combating these two agents of destruction. Indeed, this interrelation of 

 insects and chestnut blight presents a new and complicated problem which 

 will require a great deal of exact scientific investigation before we shall be 

 warranted in arriving at conclusions or giving specific advice on methods 

 of control and prevention. 



EXTENSIVE INVESTIGATIONS 



The importance of having the best information that can be secured on the 

 whole subject of insects in their relation to the chestnut has led to the under- 

 taking of an extensive investigation under a special project of the branch of 

 Forest Insects of the Bureau of Entomology. This investigation will be ex- 

 tended into all parts of the country where the chestnut is, or has been, an 

 important forest tree, and especially in the States and sections where the 

 people representing the private, municipal, and State ownership manifest a 

 special interest in this phase of the problem. State officials can render a 

 service to their State by public recognition of the work and by offering such 



