408 N. E. MCINDOO, 



(c) Effects with elytra and wings pulled off 443 



The olfactory sense of Epicauta pennsylvanica 443 



(a) Effects with antennae pulled off 444 



(&) Effects with elytra and wings pulled off 444 



Summary 447 



Discussion 451 



Literature cited 455 



Explanation of plates I. and II 456 



INTRODUCTION AND METHODS. 



In the investigation here recorded two objects have been 

 kept in view: (i) To make a careful study of the morphology and 

 physiology of the olfactory pores of beetles, and (2) to determine 

 experimentally whether or not the olfactory organs lie in the 

 antennae. 



Since those investigators, who have performed experiments on 

 beetles with mutilated antennae, have failed to study sufficiently 

 the behavior of the insects investigated, the responses observed 

 have misled them in determining the seat of the olfactory organs. 

 Entomologists are generally agreed that the organs of smell in 

 beetles lie in the antennae, but when the results of those who have 

 performed experiments on beetles are carefully considered, it 

 is seen that some beetles with amputated antennae smell prac- 

 tically as well as unmutilated ones, while other beetles are 

 materially affected when the antennae are mutilated. Hicks 

 (1857 and i860) discovered some peculiar organs (called olfactory 

 pores by the present writer) on the wings and legs of beetles 

 and he suggested that they have an olfactory function. Lehr^ 

 discovered the same organs on the peduncles of the elytra of 

 Dytiscus marginalis. The present writer ('14a and h) made a 

 comprehensive study of the olfactory pores in Hymenoptera and 

 he ('14c) gives a complete review of the literature pertaining to 

 the sense of smell in insects. The present paper embodies the 

 results of a careful study of the olfactory pores in Coleoptera in 

 much the same manner as pursued on those in Hymenoptera. 



To obtain material for the study of the disposition of the 

 olfactory pores, adult specimens were used. In regard to prepar- 



1 Lehr's paper, which deals only with the morphology of these organs, was over- 

 looked until after my paper had been sent to press. Lehr has not seen any of my 

 papers on this subject because my first one ('14a) appeared only three months 

 before his, and my second one ('146) appeared in the same month as his. 



