THE CHEMICAL SENSITIVITY OF THE TARSI OF 

 CERTAIN MUSCID FLIES. 



(Phormia regina MEIGEN, Phormia terrx-novx R.D. 

 AND Lucilia sericata MEIGEN.) 



DWIGHT ELMER MINNICH. 

 DEPARTMENT OF ANIMAL BIOLOGY, UNIVERSITY OF MINNESOTA. 



INTRODUCTION. 



Experiments previously published by the author (Minnich, '21, 

 '220, J 22b) have shown that the tarsi of certain butterflies 

 possess sense organs which are exceedingly sensitive to contact 

 chemical stimulation. These chemoreceptors are of such impor- 

 tance that a more general knowledge of their occurrence and 

 function in insects is highly desirable. The data presented in 

 this paper are the results of experiments on three common muscid 

 flies, Phormia regina Meigen, Phormia terrx-novx, R.D., and 

 Lucilia sericata Meigen. For the identification of these flies 

 I am indebted to Dr. J. M. Aldrich of the United States National 

 Museum. The methods employed in these experiments are, in 

 general, similar to those employed with butterflies, the results 

 in both cases having been obtained by the use of proboscis exten- 

 sion as an indication of stimulation. 



MATERIAL AND METHODS. 



The experiments were carried out in the spring and summer 

 months. In the first experiments, therefore, the flies were indi- 

 viduals which had hibernated, whereas in the later experiments 

 they were individuals which had emerged the same season. All 

 of the flies were captured, usually with a net, either from walls 

 where they came to sun themselves in the early morning hours, 

 or from waste cans to which they were attracted by the odor of 

 decomposing organic matter. 



The flies were transferred in bottles to the laboratory where 

 each animal was etherized, its species and sex determined, and 



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