UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 965 ^^ 



Contribution from the Bureaa of Entomology 

 L. O. HOWARD, Chief 



jrC^^^t. 



Washington, D. C. 



October 18, 1921 



CONTROL OF THE ARGENTINE ANT IN CALIFORNIA CITRUS 



ORCHARDS. 



By R. S. WoGLUM, Entomologist, and A. D. Borden, Scientific Assistant, Fruit 



Insect Investigations.^ 



CONTENTS. 



Introduction 1 



Relation of the ant to the citrus industry 2 



Other relations 4 



Distribution 4 



Characteristics and habits 6 



Control 9 



Banding 9 



Trap nesting IS 



Poisoned sirups 20 



Control— Continued . 



Factors influeneuig control 34 



Control on marginal trees 37 



Clean culture 38 



Control on house lots or about build- 

 ings 40 



Comprehensive demonstration of con- 

 trol 41 



Summary 41 



INTRODUCTION. 



Supposedly introduced into the United States at the close of the 

 nineteenth century the Argentine ant {Iridomyrmex humilis Mayr) 

 has since become widely distributed through the more temperate 

 regions, where its complete occupancy, in long-infested localities, 

 and its onmivorous habit bear an important relation to crop pro- 

 duction and food storage and rank it as one of the most annoying of 

 household pests. Its discovery in 1908 in cities bordering San Fran- 

 cisco Ba}" resulted in the initiation of a control campaign under the 

 direction of Prof. C. W. Woodworth, of the Universit}- of California, 

 and subsequently led to the development of an arsenical poisoned 

 sirup of considerable merit. 



The Argentine ant was recorded in citrus orchards in California 

 almost from the date of its reported presence in the State. It 

 appeared to cause no alarm to orchardists, however, usually remained 

 unnoticed except about the buildings, and where observed was classed 



1 Photographs by senior writer; figure 3 drawn by Miss A. Motter. Mr. Woglum resigned from the 

 Bureau of Entomology September 11, 1920. 

 48155°— 21— Bull. 905 1 



