GIPSY MOTH TREE-BANDING MATERIAL. 6 
the outside territory are often located on isolated apple or oak trees 
and in open woodlands which are situated on slopes or elevations 
where the wind plays an important part in the dispersion of the small 
larvae. Infested trees are also frequently located near or in the stone 
walls so common in New England, and eggs deposited in the stone 
walls are very difficult to find and to treat. Under such conditions 
bands are very effective in preventing newly hatched larvae from 
crawling out of walls into trees that have been cleared of egg clusters, 
thus preventing also rapid and long-distance wind spread of the 
larvae. 
Bands were at one period used quite extensively in heavy infesta- 
tions of the gipsy moth along roadsides where it was necessary to 
protect trees upon which the egg clusters had been treated against 
the ravages of migrating caterpillars from adjoining woodlands. 
This served to prevent caterpillars from ascending trees that have 
branches overhanging the road, from which they could spin down by 
means of silken threads, be caught by passing vehicles, and be dis- 
persed by that means. 
MAKING GIPSY MOTH TREE-BANDING MATERIAL. 
MATERIALS USED. 
A. Coal-tar neutral oil having a density of 1.12 to 1.15 at 
20° C. 
B. Hard coal-tar pitch, melting point about 49° C. 
C. Eosin oil, known as first run " kidney," having a viscosity 
of 52 at 100° C. tested with a Saybolt universal vis- 
cosimeter. 
A neutral or nearly neutral coal-tar oil must be used, as coal-tar 
acids are sometimes injurious to trees. 
As the rosin oil is the result of crude distillation, the grade is not 
constant, varying in color, viscosity, and acidity. Some rosin oils 
are light to dark brown, some black, others dark blue, and some are 
possibly of other shades. 
Some rosin oils contain more free acid than others, and usually 
those with the higher acid content give the best results. On the 
other hand, if too .highly acid, the mixture saponifies so quickly 
that it becomes too thick before the last addition of coal-tar neutral 
oil is made, with the result that when the latter is added it will not 
mix properly, thus making a poor product. 
The rosin oil that gave the best results was of a medium to dark 
brown color, having a viscosity of 52 at 20° C. tested with a Saybolt 
universal viscosimeter and containing 26 per cent free acid. This 
oil saponified in from 4 to 10 minutes ; those which saponify rapidly 
are not so satisfactory to use. 
