31 



EXPEKIENCE WITH OkCHAKD FuMIGATION. 



Having- decided on an extensive practical trial of orchard fumi- 

 gation with li3'drocyanic acid g-as, I found it necessary first to pro- 

 vide expert advice and supervision with respect to the practical 

 operation, with which none of my office force had any personal 

 acquaintance, and for this purpose, after considerable correspond- 

 ence, I secured the aid of Prof. Charles W. Woodworth, Assistant 

 Professor of Entomolog-y at the University of California and Ento- 

 molog-ist of the California Ag-ricultural Experiment Station. Pro- 

 fessor Woodworth being- a g-raduate of the University of Illinois 

 was well known to me personally, and was particularly useful to 

 us because he had made a special study of fumig-ation operations 

 iu California. He had, in fact, published an elaborate bulletin on 

 "Orchard Fumig-ation,"* which was the principal reliance of 

 economic entomolog^ists interested, and remains to-day the best 

 brief practical treatise on the subject. 



Arriving- in May, 1899, he inspected parts of our infested dis- 

 tricts, planned our equipment and superintended its manufacture, 

 coached our first fumig-ating- squad, and supervised its practice 

 work — first on the Experiment Station farm, at Urbana, and later 

 on premises infested by the San Jose scale at Monticello, in 

 Piatt county. 



Description of Ecjiiipuicut. — Our tents to cover infested trees 

 and confine the insecticide g-as liberated under them were all made 

 of eig-ht-ounce canvas, treated in two different ways to make them 

 impermeable to the g-as. The first lot were thoroug-hly sized with 

 flour paste and covered, when dry, with a thin black paint; and 

 the second lot were saturated with boiled linseed oil and left spread 

 out until dry. The latter method of preparation proved the more 

 satisfactory and durable. The paint was likely to wear and crack 

 with use, and the sizing- and painting- were more laborious 

 and costly than filling- with oil. The latter operation was conve- 

 niently and rapidly performed (as shown in Plate I. ) by the aid of a 

 common spray pump provided with an adjustable nozzle. Great 

 care was necessary that the oil in the tents should be thoroug-hly 

 dried out before they were folded, as otherwise they were liable to 

 heat, with the effect to destroy the cloth if not to set up spontane- 

 ous combustion. 



The fumig-ation outfit consisted of forty-seven tents, three 

 pairs of lifting- poles, and several sets of generators for the prepa- 

 ration of the g-as. All except the smallest tents were flat oblong- 



* Bull. \ll. Calif. Aifi-. E.xper. Station. 



