THE TRACKING INSTINCT IN A TORTUGAS ANT. 



By Alfred Goldsborough Mayor. 



In the preparation of this paper it is a pleasure to acknowledge 

 my indebtedness to Professor William M. Wheeler for his identifica- 

 tion of the ant in question and for references to the literature. All 

 papers previous to 1910 are referred to in Wheeler's masterly work 

 ''Ants," published by the Columbia University Press, while the 

 studies of later authors, such as Pieron, Turner, Santschi, etc., are 

 referred to by R. Brun (1914, Rie Raumorientierung der Ameisen und 

 das Orientierungs problem in allgemeinen, 234 pp., 51 fig. Jena). 

 Another important paper is by V. Cornetz (Les exploration et les 

 voyages des fourmis, 192 pp., 83 fig. Paris, 1914). In this brief paper 

 we will not attempt to review the already voluminous literature, but 

 refer to it onlj^ as it relates to our observations. 



Monomoriuin destructor Jerdon, a tropicopolitan ant of East 

 Indian origin, was identified in Florida by Wheeler (1906, Entomo- 

 logical News, vol. 17, p. 265). It is a small, reddish-brown ant, and 

 is a great pest in- the wooden buildings of the Tortugas laboratory, 

 making its nests in crevices of the woodwork. So voracious are these 

 insects that we are obliged to swing our beds from the rafters and to 

 paint the ropes with a solution of corrosive sublimate, while all tables 

 must have tape soaked in corrosive sublimate wrapped around their 

 legs if ants are to be excluded from them. These pests have the 

 habit of biting out small pieces of skin, and I have seen them kill 

 within 24 hours rats which were confined in cages. 



The experim-ents herein described were made on the flat wooden 

 floor of the laboratory, this flatness having possibly prevented the 

 ants from orienting themselves with respect to conspicuous objects 

 or unevenness in the ground, although I have no evidence that they 

 do this under any conditions. 



In order to attract the ants, a number of recently killed house- 

 flies were impaled upon a pin; and then, upon looking over the floor, 

 one soon found an ant wandering in a tortuous course over the 

 flat surface. The pin with its lure of flies was then thrust into the 

 floor in front of this foraging ant, which would often pass v/ithin 

 0.25 inch of the lure without perceiving the flies; but if its course 

 were such that it came appreciably nearer than 0.25 inch, the ant 

 suddenly turned toward the flies, and without apparent excitement 

 appeared to "inspect" them, spending a half minute or more crawl- 

 ing over them and stroking them with its antenna?. This applies to 



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