43 



Aside from outdoor work, hydrocyanic acid gas has, in my opinion, a 

 great future for the destruction of insects in grain bins and ware- 

 houses. It has been successfully applied to greenhouses infested with 

 insects, and can be used to good advantage, even in private houses, 

 against household pests. I predict a great future for this substance 

 in entomological science. 



An illustrated detailed account of these experiments is published as 

 Bulletin No. 57 of the Maryland Experiment Station. 



Mr. Alwood pointed out the impossibility of determining with any 

 great certaiuty the actual distribution of the San Jose scale. He 

 stated that in Virginia he had found no difficulty in controlling this 

 insect. The work had been undertaken promptly and energetically, all 

 infested stock being uprooted and burned and the rest disinfected by 

 fumigation. He claimed to have been the first to use hydrocyanic acid 

 gas, more particularly for disinfecting nursery stock, in the East, and 

 his results had been entirely satisfactory, following the formula given in 

 the reports of the Division of Entomology of the United States Depart- 

 ment of Agriculture. He had employed the gas very extensively and 

 expected to continue its use in the future. In Virginia this scale, be 

 said, was practically removed as a destructive factor in orchards. 

 Many infested orchards had been thoroughly freed from the scale with 

 the application of soap and kerosene, and others by fumigation. For 

 orchards he now uses the pure kerosene almost exclusively, and makes 

 the application at any time, thoroughly atomizing the liquid. Of hun- 

 dreds of trees treated none had been killed. The application had been 

 made at all seasons, but is preferably made in winter. In the fumiga- 

 tion of nursery stock he had buildings arranged with double compart- 

 ments, using the rooms in alternation, as a saving of time. Fumigation 

 is continued forty minutes, at the close of which an upper window and 

 a door are opened. The room is not entered until after the lapse of 

 ten minutes. The apple-root louse, Schizoneitra lanigera, which is much 

 worse in Virginia than the San Jose scale in amount of damage occa- 

 sioned, he controls on nursery stock by fumigation in the same manner 

 as the San Jose scale. 



Mr. Johnson gave a resume of the distribution of the San Jose scale 

 in Maryland. 



A general discussion followed, participated in by Messrs. Smith, 

 Marlatt, Hopkins, and others, on gas treatment, Mr. Johnson reading a 

 portion of a paper by himself relating to the effect of the gas on trees, 

 concluding with some notes on its effect on man and lower animals, and 

 particularly some experiments with a dog and chickens, all of which 

 illustrated the necessity for the greatest caution to avoid inhaling the 

 gas. 



