GIPSY MOTH TREE-BANDING MATERIAL. 7 
used in the formula heretofore stated, which had a specific gravity 
of about 1.12 at 20° C, an addition of the neutral oil should be made 
to the amount first added and to the amount last added to the mixer, 
that is, an addition should be made for every 15 points rise in the 
H viscosity of the rosin oil. 
Table I. — Method of adjusting formula to provide for difference in viscosity 
of rosin oil. 
Weight of coal- 
Weight of coal- 
Viscosity of 
Weight of 
tar neutral oil, 
tar neutral oil, 
rosin oil. 
rosin oil. 
first addition 
last addition 
to mixer. 
to mixer. 
Lbs. 
Lbs. 
Lbs. 
52 
50 
70 
20 
67 
46 
72 
22 
82 
42 
74 
24 
97 
38 
76 
26 
If the viscosity of the rosin oil falls between these numbers, the 
amount to be used should be adjusted proportionately, and the amount 
of coal-tar neutral oil to be used should also be adjusted accordingly. 
When the viscosity of the rosin oil rises above 80 it becomes quite 
thick, and it is usually necessary, especially in cool weather, to apply 
heat to the mixing kettle in order to have it combine properly with 
the other ingredients. The amounts of pitch neutral oil mixture and 
lime to be added remain the same. 
COST OF MATERIALS. 
The cost of materials used (prices paid by the United States Bureau 
of Entomology in the fall of 1918) were as follows: The coal-tar 
neutral oil, 67^ cents per gallon (about 7.1 cents per pound) ; rosin 
oil, 59 cents per gallon (about 7.09 cents per pound) ; the hard coal- 
tar pitch, $21 per ton (1.05 cents per pound). Based upon these fig- 
ures the ingredients composing the tree-banding material cost 6.5 
cents per pound. The labor in making the material figured 1.1 cents 
per pound, the total cost being 7.6 cents per pound. These prices 
do not include containers. 
Metal containers are decidedly preferable to wooden (fig. 2) for 
storing or shipping the finished product, as the latter absorb some 
of the oil contained in the mixture. 
Over 25 tons of this material had been made by the United States 
Bureau of Entomology, at Melrose Highlands, Mass., by December 
31, 1919, and used in the gipsy moth work in New England. 
APPLICATION OF THE BANDS. 
PREPARING THE TREES. 
In the application of sticky bands to forest and shade trees, the 
usual method is to scrape off, by means of a tree scraper, the loose 
scales of bark over a surface of 3 to 5 inches wide at the place the 
