February, '15] 



FELT: FUMIGATION FOR BOX LEAF ^IIXER 



95 



at the rate of d, 10, 20 and 30 drops to a two-quart fruit jar, the ex- 

 posure being 15 and 60 minutes. The treatment was fatal to the 

 maggots and there was also serious injury to the foliage. The gas 

 penetrated the mines readily and caused the collection of moisture. 

 The latter was probably drawn from both the plant and animal tissues 

 and resulted in an early collapse of the larvae, especially where the 

 larger amounts of ammonia were employed. The mines in the treated 

 foliage had a strongly pungent ammonia odor for two to even seven 

 days after the fumigation. It is possible that by using smaller 

 amounts of this chemical 'we could secure the destruction of the larvae 

 without serious injury to the plants. Our preliminary experiments, 

 however, indicate the probability of more or less damage to the foliage. 



Flake napthalene used at the rate of one-half teaspoonful to a two- 

 quart jar and giving an exposure of five hours, resulted in the larvae 

 becoming quiescent and eventually recovering. There was no injury 

 to the plant. The twenty-four hour fumigation gave practically the 

 same results. 



Potassium cyanide, 95 per cent was used at the rate of one dram 

 with one-fourth of an ounce of sulphuric acid and three-fourths of an 

 ounce of water to 27 cubic feet, the exposure being for 15 minutes. 

 This strength is practically one-half that recommended for fumigating 

 nurserj^ stock, namely, one ounce to two hundred cubic feet of space. 

 This treatment killed some of the larvae and did not injure the foliage. 



Owing to conditions it was impossible to supplement these tests 

 by experiments under field conditions. 



Vice-President Herrick: I would like to ask Dr. Felt if he tried 

 any contact sprays like Black Leaf 40 on the foliage. 



I\Ir. E. p. Felt: We tried contact leaf sprays in the course of the 

 experiments and got absolutely no results on box leaf miner. It is a 

 thick leaf and the membrane over the mine is rather thick. 



Mr. E. N. Cory: In Maryland, there was found one infestation of 

 this insect on a hedge on a large estate.. The hedge is about 600 feet 

 long and practically two-thirds of it is infested. We have attempted 

 some preliminary experiments with cyanide but were unsuccessful in 

 our fumigation. We tried Black Leaf 40, one part to 500 parts of 

 water with the addition of two pounds of fish-oil soap and were un- 

 successful with that. We have planned to continue on this hedge with 

 contact insecticides. We will also follow Dr. Felt's work and try some 

 of his fumigation experiments on this hedge. 



Mr. E. p. Felt: One more statement entirely outside of the scope 

 of the paper. Professor Stene of Rhode Island reports fairly good 



