36 



Mr. Howard read the following : 



ON THE FUTILITY OF TRUNK AND CROWN WASHING AGAINST 

 THE ELM LEAF-BEETLE. 



By L. O. Howard, Washington, D. C. 



When the elm leaf-beetle made its first serious outbreak in New 

 Haven, Conn., in the early summer of 1895 the authorities were unpre- 

 pared and the seriousness of the matter did not enforce itself until the 

 damage was practically done. It was then too late to spray, and, in 

 fact, no apparatus was ready. They immediately, however, as the writer 

 stated before this association last year, began extensive work with 

 kerosene emulsion upon the larvae on the lower part of the trunk and 

 about the base of the tree. Nearly 14,000 elms were treated in this 

 way by the superintendent of parks, and many barrels of standard 

 kerosene emulsion were made under his supervision and distributed to 

 citizens who came for it with buckets to use upon trees in their private 

 grounds. It was considered that the scale upon which this work was 

 done was so great that it would exercise a very considerable influence 

 upon the number of the beetles during the summer of 1896. That it 

 did exercise a certain amount of such influence can not be doubted, 

 but that the insect can be kept in check by such means is entirely neg- 

 atived by the number of insects which successfully hibernated and 

 laid their eggs upon leaves the present season. In the discussion of 

 Dr. Lintner's very interesting paper upon a The elm leaf-beetle in 

 Albany" at our last meeting Dr. Lintner stated in regard to the pub- 

 lished accounts that many of the larva? had dropped from the tree 

 instead of traveling down the trunk, although the idea seemed 

 reasonable it was not confirmed by his observations. He instanced a 

 Scotch elm upon his own grounds which has long and somewhat droop- 

 ing branches which extend over an extension of the house, but he was 

 not able to find at any time during the season a single larva or pupa 

 upon the roof of the extension, although fallen leaves in corners offered 

 convenient resting places for them. Nor had he noticed in all of the 

 hours that he passed under the elms in his study of the insect one of 

 the larvae upon his clothing or known it to occur upon others. Refer- 

 ring to this statement, the writer in the course of his discussion 

 remarked that in his opinion not above 60 per cent of the insects upon 

 large trees crawl down the trunk to the ground, the others falling from 

 the branches direct or undergoing the transformations upon the rough 

 bark or upon larger trees in the main crotches. In this statement the 

 writer was corroborated by Mr. Smith, who further stated that he had 

 known them to climb fences and transform in the crevices. 



The statement made at the last meeting that not above 60 per cent 

 of the insects crawl down the trunks of large trees under normal con- 

 ditions, although it seemed to the writer to indicate an estimate which 

 was about correct, must be altered, as the result of certain observations 



