CONTROL OF ARGENTINE ANT IN CALIFORNIA. 9 



considerable period. Often after the Argentine ant has been eradi- 

 cated in an orchard by control means the native ants will come in, but 

 gradually the area will be retaken by the imported ant unless pre- 

 vented. In comparison to this it is interesting to note the social 

 habits of Argentine ants among themselves. They do not fight one 

 another nor do members of different colonies disagree. In fact, trails 

 from different colonies often converge and an interchange of workers 

 may take place. 



The workers are active throughout the day and night and feed al- 

 most continuously if not affected by temperature conditions. On 

 cool, foggy, or frosty mornings with a temperature below 50° F. the 

 activity of the ants is greatly retarded and they become slow and 

 sluggish in their movements. Small colonies become almost inactive. 

 Only a small percentage of the workers leave the colony to forage, the 

 majority remaining to protect and care for the ant nest. 



CONTROL. 



The development and spread of the Argentine ant appear to be 

 governed very largely by food supply and meteorological conditions. 

 From natural enemies such as exert a restraining influence on most 

 injurious insects this species is remarkably free and no record of even 

 temporary control by this means has come to notice in the historj- of 

 the pest in this country. Therefore, artificial control is the one 

 source of relief once the ant has become established. 



The first efforts toward control of the Argentine ant on citrus trees 

 in southern California were made in July, 1915, and confined to band- 

 ing with commercial sticky tree-banding material, a substance 

 widely used to prevent insects ascending plants. Further experi- 

 ments in repressive measures, including the use of the sticky mate- 

 rial compounded with other substances, banding with corrosive- 

 sublimate tape, and the use of pyrethrum and sodium fluorid, were 

 carried on until the appearance, during the latter part of 1916, of 

 Bulletin 377 of this department, by E. R. Barber, which presented for 

 the first time a successful method of ant eradication. The superi- 

 ority of eradication over control by repressive measures was imme- 

 diately apparent, and subsequent experiments have been carried out 

 with this in mind. 



BANDING. 



Sticky Tree-Banding Material, 

 experiment 1. 



During the latter part of September, 1915, an experiment with 

 sticky tree-banding material was started in an orchard of 1.135 trees, 

 each of which was attended by heavy trails of ants. Bands Sk to 5 

 48155°— 21— Bull. 9G5 2 



