2 FUMIGATION METHODS 



Department of Agriculture for 1887, and in "Insect 

 Life," Vol. III., by way $>f explanation, he wrote me 

 March 21, 1898, as follows : " During the summer of 

 1886 I was employed by the United States Depart- 

 ment of Agriculture to carry on a series of experiments 

 at lyos Angeles, California, against the cottony cushion 

 scale {Icerya purchast), but owing to an insufficient 

 appropriation I was laid off on August ist of that 

 year. As no perfect remedy had at that date been 

 discovered, I determined to experiment with gases 

 in a private capacity and at my own expense. 

 Accordingly, during the first wfeek of the following 

 month I began experimenting with hydrocyanic acid 

 gas, which I thought would be the best for the pur- 

 pose, owing to its very poisonous qualities, the rapidity 

 of its generation, and the readiness with which it dif- 

 fuses itself in the air. Nobody suggested to me to 

 try this gas. It was not until the following July that 

 the Department of Agriculture again placed me on its 

 rolls." 



It will thus be seen that Mr. Coquillett continued 

 to work on the problem of destroying the scale, though 

 at his own expense, and in September, 1886, began 

 seriously to study the methods of fumigation. Fumi- 

 gation with carbon bisulphide had been inaugurated 

 on a small scale by J. W. Wolf skill and his very able 

 foreman, Alexander Craw, at L,os Angeles. At their 

 place Mr. Coquillett began his experiments, profiting 

 by the facilities here provided. It was here he first 

 conceived the idea of using hydrocyanic acid gas. 

 About six months were required to perfect methods. 



The result of the work in the Wolf skill orchards 



