33 



had been drawn forward far enough one tent man loosened the 

 pulley rope and let the pole fall, the pole man detached the rope 

 from the canvas and set the pole up at another tree, while the tent 

 men ran a binding- rope about the tent below the tree top, drew it 

 closely, and tied the ends togfether. The borders of the tent were 

 then laid close to the g^round, and weighted with earth if high 

 wind made this necessary, and the tent was carefully searched for 

 possible leaks. 



The fumigator prepared the charge according to the formula 

 of the California Bulletin for winter treatment. He measured the 

 circumference of the tent at its largest diameter and estimated the 

 distance over the top from his knowledge of the length and width 

 of the tent in use. The "acid man" measured the required 

 amount of water and acid, poured them into the generator and held 

 up the border of the tent while the fumigator put the generator in 

 place near the trunk, charged it, and withdrew. He then quickly 

 dropped the tent, seeing that it lay close to the earth, permitting 

 no gas to escape. 



The chemicals used were in the proportions indicated for a 

 .3% gas in the table on page 28 of the California Bulletin. From 

 the fact that the tent was usually drawn in below the head bj- a 

 rope while the measurement was made round the top of the tree at 

 its greatest diameter, the proportion of gas was in most cases con- 

 siderably stronger than .3%. After charging the tent with the 

 gas it was left to stand forty minutes, at the end of which time it 

 was taken down and moved to another tree. 



Prdimincvy Operation at Moniiccllo. — Fumigation can be done 

 while the leaves are on the trees only at night or on dark and 

 cloudy days, and our first attempts being made in June (1899), the 

 work was done entirely at night. The infested place nearest to 

 my office and most convenient of access was Monticello, in Piatt 

 county, where the San Jose scale had been found on a few town 

 lots containing various species of fruit and ornamental trees and 

 shrubs. 



A brief operation there demonstrated at once the impractica- 

 bility of satisfactory fumigation work on the miscellaneous stock 

 of an ordinary town lot. The trees infested were of various shapes 

 and size, some of them too large to be inclosed by a tent. Trees, 

 shrubs, and vines were often mingled in thicket-like masses which 

 could not be covered securely, and the various kinds of vegetation 

 which it was necessary to treat were variously sensitive to the 

 withering action of the gas. 



After one night's work of my field party on the grounds of a 



