6 NEW YORK STATE MUSEUM 



Streets, and conversely municipal authorities are prone to state that 

 injury to public trees is due to the pests swarming thereto from 

 neglected private grounds. The facts of the case are that both of 

 these insects are very local in habit. This is a necessity in the case 

 of the tussock moth, because the female is wingless and as a conse- 

 quence the species relies for dissemination on the very limited 

 crawling powers of the caterpillar or upon their being carried by 

 other agencies. The elm leaf beetle, on the contrary, flies readily, 

 but for some reason or other it is very local in its habits and not 

 infrequently one may see magnificent trees infested with hordes of 

 beetles and larvae, while within a block, sometimes within 50 feet, 

 other elms may be practically free from the pest. These facts are 

 of g-reatest importance to all interested in the welfare of shade trees, 

 since they demonstrate beyond question the possibility of protecting 

 the trees on our public streets, irrespective of what is done by 

 private citizens, or conversely, the practicability of keeping the pest 

 in check on private grounds, even though little or no repressive 

 work is done upon those adjacent. 



White marked tussock moth 



Hemerocampa leucostigma Abb. & Sm. 



This insect, preeminently a pest on city and village trees, occa- 

 sionally proves a veritable scourge over considerable areas. Some 

 cities appear to be more afflicted in this way than others. Buffalo 

 seems to have been specially unfortunate in the last six or seven 

 years. The summer of 1906 was marked by extensive depredations 

 in a number of cities and villages throughout the State, thus dupli- 

 cating the experience of 1898. It will therefore be seen that serious 

 injuries by this caterpillar are more or less periodic. This is to be 

 explained by the fact that the species has a number of natural 

 enemies which assist materially in keeping it in subjection. The 

 destructive outbreaks are examples of what might occur annually 

 were there no parasites to check the work of this voracious leaf 

 feeder. The cause of this native species thriving so greatly in cities 

 and villages during recent years is explained by the abundance of 

 the English sparrow. This bird will not eat the caterpillars and 

 drives away many of the native forms which, in earlier days, were 

 of great service in devouring these hairy pests. 



