CONTBOL OF ARGENTINE ANT IN CALIFORNIA. 11 



The size of the orchard prevented each band receiving the same 

 careful attention given in Experiment 2. Instances were noted 

 during the autumn where the bands on slightly attended trees were 

 bridged within an hour following the application. 



CONCLUSIONS. 



The conclusion to be reached from these two experiments is that 

 the constant attention required to make sticky tree-banding material 

 an effective barrier to ants on heavily infested citrus trees renders 

 the method impracticable in orchard work. It might be used to 

 advantage on a few trees which can be given the necessary attention, 

 as, for instance, on house lots or about buildings. 



The general belief that sticky tree-banding material is injurious 

 to citrus trees when applied directly to the bark has been found 

 erroneous. The writers have never seen a citrus tree killed as a 

 result of this treatment. In 1915, 40 three-year-old nursery trees 

 were banded. Examination of the bark beneath the bands one year 

 after application showed the bark perfectly green and healthy. The 

 sticky material on 100 trees banded in September, 1915, was scraped 

 off in July, 1916. In no instance was there certainty of injury to 

 the bark or cambium. Examination of hundreds of trees which 

 have been banded with sticky material for periods ranging from 1 to 

 5 years have failed to show definitely a single instance of severe 

 injury attributable to the bands. A disease kno^^^l as gummosis is 

 prevalent throughout southern California especially on heavy soils. 

 Exudation of gum from this disease, beneath the bands or closely 

 adjacent, and the accompanying diseased tissues revealed by remov- 

 ing the band, have been sometimes attributed to the banding with 

 sticky material, although no cases have been observed where this was 

 definitely the cause. Applications to trees soon soften the bark 

 beneath somewhat. After about one year the exposed surface of 

 the sticky material becomes glazed and by the second year a hard 

 exterior coating is found and only the substance adjacent to the tree 

 remains moist and sticky. In due time, depending on the thickness 

 of the sticky layer, the entire band becomes hard, and subsequently 

 is broken by the expanding growth of the trunk. The bark where 

 exposed to the air dries and assumes its normal consistency and 

 appearance. Heavy bands may require several years to dry. 



Possible injury from sticky tree-banding material might arise from 

 removal of heavy bands within a year following their application or 

 before they are somewhat dried out. In one case trees heavily 

 banded in September were scraped the following July. The bark 

 was so injured by the workmen in removing the sticky material that 

 a very weak solution of corrosive sublimate was used to disinfect 



