April, '09] JOURNAL OF ECONOMIC ENTOMOLOGY 167 



be as certain as possible that no possible factor has been overlooked. 

 Some small thing may turn out to be most important in the end. 



]\Ir. Skinner : I don't know that this is exactly in the line of dis- 

 cussion of this paper, but it is simply a thought that has interested 

 me in regard to economic work for some time, and men like Doctor 

 Fernald, who have student investigators, have an opportunity to take 

 up these studies. It seems to me that with regard to stored grains we 

 can get rid of a good many insects. I would suggest a very simple 

 method, and that is to replace air in proper receptacles : for instance, 

 ^vith a material like carbonic acid. It seems to me that it would be 

 a most effective method, with almost no expense, and it would obviate 

 the question of poisons as we ordinarily understand them. I have 

 made some investigations of these points in a very limited way, and it 

 seems so practical and so self-evident that I bring it before the Asso- 

 ciation in the hope that some who have the opportunity will take it 

 up. It is such a simple matter to deprive insects of air, and it is so 

 effective when it is done, in spite of what some people say to the con- 

 trary', that I am in hopes that the subject may be investigated. 



Mr. Slingerland: I was very glad that Doctor Fernald spoke 

 about the effect of moonlight. I came across a case some years ago in 

 the Hudson River valley, where they grow violets very extensively 

 under glass. A violet house was fumigated with the usual dose and 

 one night the plants were severely injured by the gas. The only un- 

 usual factor that might have caused the trouble was that it was a 

 bright moonlight night. 



Mr. Gossard : A few years ago, in experimenting with fumigating 

 orange trees in Florida, our chemist made some tests to determine the 

 amount of gas generated by combining the acid and water just before 

 the cyanide was thrown mto it, and it gave a considerably larger vol- 

 ume of gas than if the acid and water were put together and had time 

 to cool before they were taken into the field. We could save six or 

 seven cents per tree in case of large trees by observing that point. 



Mr. J. L. Phillips: The past season in Virginia has been rather 

 dry, and some of the nurserymen have complained of injury from 

 fumigation. In one case I found that the stock had been exposed to 

 freezing weather for about twenty-four hours, and this might have 

 caused the trouble in this case. "We have had several other complaints 

 this year, and I would like to Imow whether this has occurred in other 

 states. 



The method of the diffusion of gas has seemed to us to be very im- 

 portant, from the fact that some of the nurserjonen pack the stock so 

 closely in the house that it is impossible for the gas to circulate. This 



