58 THE ARGENTINE ANT. 



will frequently encircle the spot which they ultimately hope to attain. 

 They will never attempt to avoid a hand threatening from any 

 direction as a spider will do, but will continue going ahead until 

 their antennae touch the obstacle. The manner in which they 

 religiously follow their trails and the confusion which results when 

 these trails are destroyed proves that they do not trust to a sense of 

 sight in traveling. This is illustrated again by the fact that they are 

 active all night in the darkest situations. 



HEARING. 



The sense of liearing in these insects is not acute, even if indeed it 

 be developed at all. The ants are not disturbed by ordinary noises, 

 such as talking or working about the nests. If, however, one emits 

 a loud shout within a few inches of the formicary, or fires a pistol 

 near it, the ants are thrown into the confusion and excitement 

 characteristic of them when disturbed. It seems not impossible 

 that in such cases they have detected actual vibrations of the surface 

 on which they are located, due to the action of the sound waves. 

 Strangely enough, in situations where loud noises and vibrations are 

 of constant occurrence, the ants become accustomed to them. Thus 

 at New Iberia, La., we found ant colonies between and under the 

 ties of a railroad track over which many trains passed daily. 



CANNIBALISM. 



Cannibalism in any form is extremely rare in the case of this 

 species, and true cannibalism has not yet been observed. The only 

 thing at all approaching it was observed in the case of a colony kept 

 in our formicarium, the workers of which developed a habit of eating 

 the eggs as fast as they were deposited by the queen. This colony 

 was established in an artificial formicary on November 27, 1907, and 

 from that time until the early part of July, 1908, larvae were reared 

 more or less continuously and in the usual numbers. In July it was 

 noticed that the number of immature stages became steadily smaller, 

 and on July 28 a quick removal of the cover from the cage disclosed 

 several workers in the act of eating eggs. Thinking that this might 

 be due to lack of sufficient food of an animal nature fresh meat was 

 at once furnished the colony and was thereafter kept continually 

 accessible. In spite of this the egg-eating habit continued until 

 November 5, 1908, all eggs being eaten within a few hours after their 

 deposition by the queen. By this tune the number of workers in the 

 colony had been reduced to six, and by November 1 1 the queen and 

 remaining workers were dead, the colony having apparently been 

 exterminated tlirough lack of any maturing workers to replace those 

 dying from old age and accident. 



