226 Bulletin 308 



At the suggestion of P. J. Parrott, of the Geneva Experiment Station, 

 " Tree Tanglefoot " was tried on a few trees. This sticky substance was 

 spread on the bark of the tree with the hope of capturing the moths that 

 normally rest in this situation. Its use was abandoned because it did 

 not catch enough moths and because of the labor required to apply it to 

 such a large surface. It also gave the trees an unsightly appearance. 



Attempts to kill the eggs. — The eggs appear so delicate that we thought 

 it might be possible to kill them with some contact spray. On June 9, 

 19 10, we sprayed three trees thoroughly with " Nico Fume " tobacco 

 extract, i ounce in 5 gallons of water, adding two cakes of laundry soap 

 to each 25 gallons of the mixture. At this time the eggs were abundant 

 but no mines were visible, showing that the eggs had not yet begun to 

 hatch. Especial care was taken to hit the underside of the leaves where 

 the eggs are deposited. An examination of these trees later in the season 

 showed that this spraying did practically no good; the sprayed trees were 

 as badly infested as the unsprayed. It may be that a spray stronger in 

 nicotine would be more effective. No further experiments were made 

 along this line. 



Attempts to kill the larvcB in the mines. — In view of the fact that it is 

 possible to kill the larvae of the Elm Sawfly Leaf -miner {Kaliosysphinga 

 ulmi Sundeval) while in their mines by spraying the leaves with a nicotine 

 and soap solution, we thought the same treatment might be effective 

 against the smaller and apparently more delicate plum leaf-miner. Ac- 

 cordingly, on July 6, 191 1, we sprayed 32 trees thoroughly with " Black- 

 leaf 40 " tobacco extract, i part in 800 parts of water, adding about 2 

 pounds of whale-oil soap to each 50 gallons. At that time about one half 

 of the larvae had left the mines and most of those remaining in the leaves 

 were in the blotch part of the mine, protected only by the thin outer layer 

 of the leaf. An examination of these trees twenty-four hours later showed 

 that less than 10 per cent of the larvae had been killed. 



Cultivation as a means of control. — Early in the progress of this work 

 Professor Slingerland (Proc. N. Y. State Fruit Growers' Association, 

 p. 122, 1909) thought that this pest might be controlled by thorough 

 cultivation of the ground beneath the trees after July 1 5 and during May. 

 This would scatter and bury the majority of the cocoons. As the moth 

 is a very delicate creature it would probably be unable to reach the surface 

 after leaving the cocoon if covered by even a thin layer of earth. 



As stated above, the heavy infestation of the Hooker orchard was 

 probably induced by the strip of undisturbed sod beneath the trees, which 

 afforded ideal winter protection to the cocoons. Acting on Professor 

 Slingerland's suggestion, the owners plowed up the strip of sod under the 

 trees in the fall of 1909, and have continued thorough cultivation both 



