52 NEW YORK STATE MUSEUM 



the beetles were placed upon the leaves. There was very little 

 feeding the first day, more the second and eventually the insects 

 succumbed as recorded in 1899. The important point is that elm 

 leaf beetles will feed upon poisoned foliage only when compelled 

 by hunger and, as a consequence, thorough spraying is necessary 

 if one would secure satisfactory results. 



Results of spraying for elm leaf beetle in New York State. 

 We have repeatedly stated that well-sprayed trees should keep 

 their foliage green and vigorous throughout the season. Further- 

 more, trees weakened from injury by this insect should be able to 

 regain their vigor in large measure. Systematic spraying for 

 this pest has been in progress in some New York communities 

 for over ten years, and it may be instructive to review the situation 

 and see what has been accomplished. There is no question but that 

 these annual applications have been of material service in protect- 

 ing the trees. This is quite different from admitting that the 

 spraying has in all cases been satisfactory. The defects in treat- 

 ment as ordinarily practised were especially apparent in 191 1, be- 

 cause the extreme drought of that season served to emphasize the 

 work of the beetle and led many to question the efficacy of the 

 application. The Entomologist at that time examined the trees in 

 several communities and was forced to conclude that the unsatis- 

 factory results were due to poor work. The foliage of many trees 

 here and there and that of most of the lower branches were in 

 relatively good condition, while numerous trees had much of the 

 foliage badly browned, this being especially true of the upper 

 branches in the taller trees. Too many have tacitly assumed that 

 any kind of spraying would give results, whereas, as shown by 

 experiments detailed above, nothing but the most thorough work 

 will result in keeping the trees in full vigor. 



The elm leaf beetle, as is well known, first became well estab- 

 lished in the lower portion of the Hudson valley. There are a 

 number of cities and villages in that section where elms, especially 

 the Scotch and English elms, are conspicuous by their absence. A 

 very large proportion of such trees have succumbed to this pest 

 in the city of Troy since 1895. The writer has watched this pro- 

 cess of destruction in Albany and vicinity for over fifteen years. 

 The earlier portion of this period was marked by extensive local 

 injuries to European elms which were subsequently approximated 

 only in 191 1 when the beetle was so generally destructive to 

 American elms. It was a time when the necessity of spraying was 



