NO. 9 OLFACTORY SENSE OF INSECTS AFcINnOO 3 



yEliani (1744) asserts that bees smell anything- with a foul odor or 

 anything smeared with odors, and that they cannot tolerate an offen- 

 sive smell, nor do they like sweet, delicious odors. 



Rosel and Klemann (1747) remark that it is clearly understood 

 that certain butterflies have a very acute sense of smell and that one 

 sex certainly perceives the odor of the other from a distance. 



Romanes (1877) is certain that moths smell, although they may 

 detect the odor from ammonia through their whole system. 



The Peckhams (1887) in their experiments on wasps used two 

 essential oils — peppermint and wintergreen — maple syrup, and warm 

 and cold chicken bones. They say : 



We conclude from these experiments tliat wasps have a strong sense of 

 smell, but that they pay little attention to odors, however powerful, which do 

 not denote the presence of sometliing which they can utilize as food. 



From the foregoing it is evident that the belief in a sense of smell 

 in insects is general and that some insects are able to distinguish 

 between various odors. From the time of Aristotle to the present 

 no one has ever denied that insects can smell, yet no one has ascer- 

 tained the relative sensitiveness for any particular species. 



SPIRACLES AS SEAT OF OLFACTORY ORGANS 



Sulzer in 1761, according to Lubbock (1899), was the first to 

 suggest that the spiracles are the seat of the olfactory organs. Later, 

 however, he abandoned this view and adopted the antennal theory in 

 1776. 



Dumeril ( 1797) asserts that all insects possess a more or less acute 

 sense of smell. Fie was the first to advocate strongly the view that 

 insects, like all other animals that live in the air, have their olfactory 

 organ located at the entrance of the respiratory system. The air 

 charged with odoriferous particles passes into the tracheae through 

 the spiracles and here these particles stimulate multitudes of nerves 

 and thus the sensation of smell is produced. He thought that the 

 tracheal walls consist of a membrane which is clothed with olfactory 

 nerves, against which the odoriferous particles from foreign bodies 

 strike. Later the same author (1823) remarks that the perception 

 of odors is then, like all the other sensations, physical — a kind of 

 touch in which the bodies, should that be their nature, impinge upon 

 the olfactory nerves. Dubois (1890) held the same opinion, saying 

 that the first excitation is a mechanical one, like that which occurs 

 in the sensation of touch. Hermbstadt (181 1) asserts the opinion 



