246 NATURAL ENEMIES UF THE ARGENTINE ANT. 



through correspondents in South America in regard to its natural 

 enemies, but no definite information was obtained. 



With one exception, the official entomological records in 

 South Africa contain no reference to natural enemies of the 

 Argentine ant. On one occasion the writer, while examining a 

 nest of this ant in the Botanic Gardens, Kingwilliamstown, Cape 

 Province, observed a fly pick up two ant larvre in succession, suck 

 out the juice and void the larval skins. In the ordinary course 

 the only chance a fly would have of devouring the larv?e would be 

 when a nest of ants was accidentally broken open or turned out in 

 the process of cultivation. But the worker ants are so quick to 

 secrete the larvae and pup^e that the fly would in all probability go 

 away hungry, for it seems very unlikely that it would be able to 

 rob a worker ant in the act of transporting a larva. The writer 

 has not observed any other instances of the Argentine ant being 

 attacked in any stage. 



Although practically immune from attack, the Argentine ant 

 in its turn is very aggressive, and successfully attacks quite a list 

 of insects, including injuriotis as well as beneficial s])ecies. In 

 the Cape Peninsula it has maintained its reputation for intoler- 

 ance towards other species of ants. In areas overrun by the 

 Argentine ant the writer has not found any other ant except 

 an occasional colony of Dorylus helvolus- On the outskirts of 

 the infested area native species of ants are to be found. If the 

 native species disappear as the Argentine ant increases, and if the 

 latter continues to spread and to thrive in widely separated 

 localities, then South Africa shotild gradually become a one-ant 

 country. This suggests that, if Argentina is the ])lace of origin. 

 South America should be a one-ant country witliin the limits of 

 the ant's life zone, unless counterbalancing forces exist. 



In a lecture before the Divisional Council of Stellenbosch in 

 Fel)ruary, 191 5, the writer suggested that, in the absence of true 

 parasites or diseases, the fact that on the whole /. hiiiiiilis was 

 not counted a serious pest in its native home could be explained 

 on the theory that in South America there are counterbalancing 

 species of ants — i.e., species that are as strong numerically and 

 individually and as sagacious in battle as the Argentine ant. The 

 fact that in the countries where it has only recently become 

 established it drives out the indigenous ants, whereas in its native 

 country other ants persist, suggests that it has been accustomed 

 to meeting stronger opposition in its original home than the 

 opposition it finds in other countries. Furthermore, the fact 

 that in certain parts of South America /. humU'is is a more serious 

 pest than in others could be accounted for by the absence of one 

 or more of the controlling species. 



In the writer's opinion, based on observations on this species 

 from the economic standpoint in South Africa for several years, 

 whatever may be the explanation for the difi'erence in the ant's 

 behaviour in South America as compared to that in the countries 

 where it has become established, so far as can be determined, 

 during the last 25 years, the respective Governments of these 



