290 Report of the Department of Entomology of thh 



The f umigators used in our experiments were provided witli smiall 

 windows, one on either side, so that the bag could be watched as 

 it fell into the acid and the action of the acid noted. 



During some of our experiments the strips of canvas at the 

 base of the fumigator were covered with dirt, as shown at Plate 

 XLVI. This method was finally discarded and bags half full of 

 sand substituted, as they were found to' be more easily handled 

 and equally effective in making the base of the fumigator tight. 

 A stout water-proof bag 6 feet long and of small diameter, two- 

 thirds full of sand, will be found convenient for this purpose. 

 Four would be required for each fumigator and could be handled 

 easily. 



The time required for moving the fumigator from one tree to 

 another and putting it in place will vary somewhat; but in our 

 experiments in an orchard of standard Bartlett pear trees two 

 men moved the fumigator from one tree to another and set it up 

 in ten minutes without unusual effort. 



SOME ADVANTAGES OF THIS STYLE OF FUMIGATOR. 



There are at least four advantages over the tent and its modi- 

 fications which may be claimed for this style of fumigator. 



1. Its cubic contents can be accurately computed, thus ensur- 

 ing correct treatment with the gas. 



2. The same amounts of chemicals are used for each charge, 

 thus avoiding the necessity of changing the amount for each 

 tree, and of weighing cyanide in the field, which usually requires 

 an extra man where three or four fumigators are in operation. 

 The slight cost of chemicals that might be saved on trees not 

 large enongh to fill the fumigator is immaterial unless the trees 

 are very small. In such cases, if there are many of them, a fumi- 

 gator of smaller size conld be used. 



3. Fewer men are required to handle it than would ordinarily 

 be required to handle a tent large enough to cover trees that can 

 be treated with the size of fumigator described. 



L As the fumigator does not rest upon the tree there is little 

 if any danger of serious injury to buds or breaking of small limbs. 



