CONTROL OF ARGENTINE ANT IN CALIFORNIA. 13 
another case of several hundred trees banded with a poorly prepared 
material, showing granules of free sulphur, a very large proportion of 
the bands were crossed within a few days following the application. 
Experience has shown that heavy 4 to 5 inch bands of a mixture of 
sulphur and sticky banding material thoroughly protected from the 
sun will keep in good sticky condition during dry weather for a period 
of 2 to 3 months, or even longer. If exposed to the sun at all, a 
dry film quickly forms and the ants cross at will. Furthermore, the 
direct sun causes the material to become very soft and to run down 
the trunk. 
Although there is no particular reason why the addition of sulphur 
should cause the sticky material to be injurious to the bark of a tree 
the precaution was taken in all our experimental work to apply first 
a protective substance. (See fig. 5.) At first 3 to 4 inch bands of 
oilcloth were applied to tree trunks by means of adhesive tape 
attached to the upper and lower surfaces, and the tree-banding 
substance was applied to this band. The difficulty experienced in 
covering irregular tree trunks with such bands led to search for an 
innocuous substance that could be painted onto the trunk and the 
most satisfactory material tried was paraffin. This was first melted 
and kept at a temperature just above the melting point when applied 
to the tree trunk. A paint brush proved satisfactory for the work. 
The paraffin under no circumstances should be at a very high tem- 
perature, else it will penetrate deeply into the bark. The require- 
ment is a superficial layer. While the ordinary grade of paraffin 
recommended for home canning proved satisfactory in thoroughly 
shaded trees in the coastal districts, in the warm interior valleys, on 
tree trunks sometimes reached by the sun, they melted on the 
sunward side and deeply penetrated the bark, causing considerable 
injury. This necessitated the use of a paraffin with high melting 
point, one exceeding 130° F. Such paraffins are purchasable of oil- 
refining companies or dealers in technical supplies. The caution 
should be observed, however, that under no circumstances should trees be 
banded with sulphur and tree-banding sticky material over a paraffin 
band in situations readied by the direct sun. 
COST. 
In 1916 the average cost per tree banded with this mixture was 
7 to 8 cents, exclusive of removing the weeds beneath the trees and 
pruning the branches. At present the cost would approximate 
15 cents. 
Pyrethrum and Sodium Fluorid. 
Sodium fluorid and pyrethrum were used singly or in mixtures 
and applied to the crotches of trees or on cotton bands around the 
trunks. (See fig. 6.) The cotton bands usually rid the trees quickly 
