6 NEW YORK STATE M,USEUM 



necessity in the case of the tussock moth, because th« female is 

 wingless and as a consequence the species relies for dissemina- 

 tion on the very limited crawling" powers of the caterpillar or 

 upon 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 greatest importance to 

 all interested in the welfare of shade trees, since they demon- 

 strate 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 there is little or no re- 

 pressive work upon those adjacent. 



Elm leaf beetle 



Galerucella luteola Miill 



The ravages of this dangerous enemy to elms has been par- 

 ticularly severe in recent years. The damage has doubtless been 

 accentuated in numerous instances by exceptionally dry weather 

 and possibly by extremely low winter temperatures. These two 

 factors afford no adequate explanation for the great increase in 

 the number of injured trees, and particularly for the general de- 

 struction of the foliage so conspicuous in many communities in 

 1910 and 191 1. It is very probable that the extension of electric 

 car service and the more general use of automobiles have been 

 of material service in disseminating a local and exceedingly 

 prolific insect, since both of these vehicles usually traverse tree- 

 lined streets and afford abundant opportunities for the collection 

 and dissemination of the beetles and thus greatly increase the 

 damage along favorite routes of travel. 



This pest was so abundant and injurious from 1896 to 1899 

 in the cities of Albany and Troy as literally to compel some 

 action or a very large proportion of the elms would have been 

 destroyed. The insect made such headway in these cities that 

 it ruined or killed about 3000 elms before the end of 1900, and it 

 is more than probable that at least 1000 additional succumbed 

 the following decade. The earlier spraying against this pest 

 produced for the most part very satisfactory results, while the 

 treatment in recent years has given indifferent returns in man}' 



