fixi-:lv-ih)\\ i)i:i<i-:i) Mi^Kcrkic chloride (Hg ci^) 



FOR THE DESTRUCTION OF THE ARGENTINE ANT, 

 IRIDOMYRMEX HUM! US MAYR. 



By Charles Wili-iam iMally. M.Sc, F.E.S., F.L.S. 



In liis article on " Measures Suggested against the Ar- 

 ;t,fentine .\nt as a Household Pest."* Prof. Wilman Newell recom- 

 mended " Ant Tape " as a repellant, because " ants of this (and 

 >ome other) species will not cross cotton cloth or tape which has 

 been thoroughly soaked in a saturated water solution of corrosive 

 'Ublimate and then dried." In his bulletin on " The Control 

 of the Argentine Ant.f Prof. C. W. Vvoodworth, in discussing 

 the \alue of corrosive sublimate as a deterrent for ants, states 

 that " The Argentine Ant seems to be very little influenced by 

 this poison, and in many experiments tried at the ant laboratory 

 lines of ants were found re-established across the |X)ison inside 

 half-an-hour after the most liberal treatment." This left me in 

 doubt as to the real value of corrosive sublimate as a deterrent 

 for ants. As I had intended vising corrosive sublimate for the 

 purpose of isolating grape vines in fumigation ex]ieriments for 

 \'ine Mealybug {Psciidococus capensis Brain) so as to prevent 

 a native species of ant ( which was attending the mealybug in the 

 vineyard), and also other insects, including mealybug, from 

 possible secondary host ])lants from crawling up the stems of 

 the vines, it was important that all doubt should be removed. 

 While preparing some "ant tape * for trial, it occurred to me 

 that its effecti\eness jjrobably de]>ended on the fine layer of 

 corrosive sublimate crystals on the surface of the tape cominu; 

 into contact with sensitive tissue on the antennae or on the feet 

 of the ants. In such case it seemed likely that finely-powdered 

 corrosive sublimate would give better results than " ant tai)e,'" 

 because the small particles would be more easily available, and 

 hence a larger (juantity would get on to the ants. There was 

 also the ix;ssibility that they would poison themselves l)y attem]>t- 

 ing to clean their feet and antenna? b}' drawing them through the 

 mouth, the same as cockroaches are said to do with sodium 

 fluoride. 



During a fine spell of weather, in August. 191.^. the Argen- 

 tine Ants were very active near the base of a large oak tree at 

 Mowbray. I surrounded the opening of the nest with a cordon 

 of finely-powdered corrosive sublimate, about one-half inch wide, 

 about an hour before sundown, the base of the tree being shaded 

 by the house. Both incoming and outgoing ants were thrown 

 into confusion immediately they came in contact with the poison. 

 Some would advance on to it and then hastily retreat along the 

 trail. Others would get to the middle of the cordon and then 



* Journal of Economic Entomology (1909), 2 [5]. 

 'rl'nh: of California But. 207 (Oct. 1910). 81. 



