CONTEOL OF ARGENTINE ANT IN ("ALIFORNIA. 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 cjuickly 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 liigh melting 

 point, one exceeding 130° F. Such paraffins are purchasable of oil- 

 refining companies or dealers in technical supplies. The caution 

 should he observed, however, that under no circumstances should trees he 

 handed with sulphur and tree-handing sticTcy material over a paraffin 

 hand in situations reached hy the direct sun. 



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 fiuorid 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 



