508 BULLETIN 333 



THE ELM LEAF-MINER 



(Kaliosyspkinga ulmi Sund.) 



The Scotch and English elms and the Camperdown elms are subject 

 to the attacks of the larva of a small sawfly, which mines the tissues 

 of the leaves. Up to 1911 no adequate or effective method of control 

 of this miner had been found, so far as the writer is aware. 



CONTROL MEASURES 



Recalling the penetrating power of certain contact insecticides, it 

 occurred to the writer that possibly the larvae might be killed in their 

 mines in the leaves before they caused much injury. It was with a 



rather forlorn hope, how- 

 ever, that a fine, small 

 Scotch elm, which had 

 been badly injured by 

 miners in previous years, 

 was sprayed in the spring 

 of 191 1. 1 



The material applied 

 consisted of " Black-leaf 



40" tobacco extract, 

 FIG. 177-- The European dm sawfly, much enlarged ^^ ^ ^ Q ^ Q ^ 



pint to 100 gallons of water, with 9 pounds of laundry soap dissolved 

 and added to the mixture. It was the intention to use but 8 pounds of 

 soap to 100 gallons of the mixture, but by mistake 9 pounds was added. 

 The application was made in May, 1911, just as the tiny mines had 

 begun to show in the leaves. The effect was certainly surprising. Many 

 of the sprayed leaves were examined during the succeeding few days and 

 every larva was found dead. Each one had evidently been killed at 

 once, the mines on the sprayed leaves not having been perceptibly 

 enlarged. The contrast later in the season between the topmost 

 branches, which could not be reached, and the lower branches was very 

 marked (Figs. 178 and 179). The leaves not sprayed were almost 

 completely mined and became withered and most unsightly. 



In 1912 these experiments were repeated on a much larger scale, there 

 being several English elms on the university campus that had been badly 

 injured for several years. A row of such elms extends along a stone 

 wall bordering University Avenue. These trees were set by the founder 

 of the University, Ezra Cornell. They had suffered severely from attacks 

 of the leaf -beetle and the miner. Some of them had been so badly in- 

 jured that they had been cut out, while those remaining bore many 



1 Journal of Economic Entomology, vol. 5, no. 2, April, 1912, p. 171. 



