BORING INSECTS 53 



years ago, to cite a familiar case, the black locust 

 was hailed as the great post- and tie-producer of 

 the future. To-day, in most parts of the country, 

 hardly a sound stick of it can be found. The 

 locust borer has made the growing of locust tim- 

 ber unprofitable almost impossible. 



The damage done to shade trees by these in- 

 sects is greater, in proportion, than that suffered 

 by forest trees. The reason is that almost all of 

 these insects prefer to attack weak trees, and 

 changing conditions have unfortunately so affected 

 our town and city trees that a very large part of 

 them are to a greater or less extent invalids. 

 They no longer make the vigorous growth they 

 made before streets were paved and fields were 

 drained, and before factories poisoned the air. 

 But if they are more susceptible, they are also 

 more valuable than they were, and we must make 

 every effort to save them. 



It is neither possible nor desirable, in a book of 

 this type, to enumerate and describe the many 

 species of insects which in one way or another do 

 physical damage to the trunks and limbs of trees. 

 The bibliography which will be found in the ap- 

 pendix is sufficient evidence of the amount and 

 availability of the literature bearing on the sub- 

 ject. The number of injurious insects found in a 

 single locality may be very small, but the number 

 of species injurious in one place or another 



