The Homing of the Hymenaptera 31 



na is the organ of a special kind of odor ; you may not be 

 able to decide whether to agree with those who claim that 

 the sense of smell is located in the antenna or with those 

 who claim that it is located elsewhere* : but in the light 

 of the following experiments, there is no escaping the 

 conviction that ants possess a well developed sense akin 

 to the olfactory sense of man. 



Paint a narrow odoriferous band across the pathway 

 of homegoing ants, or even draw your finger across the 

 trail of certain species ; immediately the procession halts 

 and those nearest the offending streak move hither and 

 thither as though lost. The confusion will not be perma- 

 nent. Presently the procession will move along as be- 

 fore. 



As a rule ants will attack any strange worker ant that 

 attempts to enter the nest but members of the household 

 will be received with open arms even after an absence of 

 several days. Take some ants from a nest, wash the nest 

 odor from their bodies, bathe them in the blood of an 

 alien colony of ants and then return them to their own 

 nest. They will be attacked, as least temporarily, as 

 strangers. On the other hand, take some ants from a 

 nest, wash the nest odor from their bodies, bathe them in 

 the blood of ants of an alien colony and then place them 

 in that colony and they will be welcomed, at least tempo- 

 rarily, as members of the household. 



However, the admission that ants have a well developed 

 olfactory or topochemical sense is no justification for the 

 conclusion that odors, by arousing chemotropisms, guide 

 them home. There are a few species of ants that do seem 



« Forel, August. The Senses of Insects. Translated by Madeod 

 Yearsley. Methuen A Co., London, 1908, pp. 73-100. 



Mclndoo, N. E. The Olfactory Sense of Insects. Smith. Mise. i^ol^ 

 63. number 9. pp. 1-63. 1914. 



The Olfactory Sense of the Hymenc^tera. Proc. Acad. 



Sci.. Philadelphia. 1914, pp. 294-341. 



