author's abstract of this paper issued 

 by the bibliographic service, may 4 



THE OLFACTORY ORGANS OF A COLEOPTEROUS 



LARVA 



N. E. McINDOO 

 From the Bureau of Entomology at Washington, D. C. 



THIRTY-THREE FIGURES 



INTRODUCTION 



The olfactory sense of adult insects is highly developed and 

 perhaps no other anhnal can smell as well as the honey bee; in 

 fact it seems that this sense has been the chief factor by which the 

 socialMife of insects has been acquired. Among honey bees the 

 olfactory sense serves not only as a means of distinguishing the 

 three castes and the different individuals in the same colony, but 

 it is also vitally important in scenting and selecting the proper 

 food. During the immature stages of insects, sexual odors, 

 should they be emitted, probably play no role as such odors, 

 but substances suitable for food are constantly emitting odors, and 

 since food is more necessary to larval forms of insects than to 

 the adult forms, it would seem that the ability to perceive odors 

 from food should also be highly developed in larvae; yet we know 

 practically nothing about the olfactory sense of larval insects. 



No one, so far as the writer is aware, has ever identified organs 

 in any larva as the ones first described in adult insects by Hicks 

 (1857) and recently named olfactory pores by the present writer 

 (1914a), although these pores have evidently been observed by 

 various systematists, for Boving ('17, PL 118, fig. 5, por) has 

 just recently seen them near the spiracles in a larva of a cocci- 

 nellid beetle. Furthermore, Nagel ('94) saw two of these pores 

 on the maxillary palpus of a larva of the stone fly, Perla bicaudata; 

 very few on the antennae and labrum of a lepidopterous larva of 

 Antherea pernyi; but a few more widely distributed on the 

 antennae, maxillae and labium of a coleopterous larva of Dytiscus 

 marginalis. Nagel's sections through these organs must have 



113 



JOURNAI. OF MORPHOLOGY, VOL. 31, NO. 1 



