THE DISTRIBUTION OF CERTAIN INSECTS OF 

 REVERSED BEHAVIOR.* 



CLARENCE HAMILTON KENNEDY, 

 OHIO STATE UNIVERSITY. 



The recent researches of Loeb, Holmes and other students of 

 animal behavior as well as the work of various entomologists on 

 the reactions of insects to definite environmental factors, has 

 given us a mechanistic interpretation of insect activities very 

 different from the anthropomorphic interpretation of the earlier 

 students. Shelf ord, Dean and others have related many insect 

 adjustments in behavior with remarkable exactness to specific 

 conditions of light, temperature, humidity, etc. 



These reactions are frequently quite specific but many of them 

 are the same for all the species of a genus. As, for instance, 

 all species in a genus are nocturnal or all are aquatic. Such a 

 generic tropism usually defines the generic habitat in a broad 

 way. Within this general habitat the individual species will 

 have individual habitats limited by other tropisms. Apparently 

 the generic tropism that defines the generic habitat is seldom 

 modified for any individual species enough that such a species 

 may exist outside the generic habitat. But apparently a com- 

 plete reversal of a generic tropism is more likely of occurrence 

 than any lesser modification. When such occurs in a genus 

 the individual species possessing this reversed generic tropism 

 has entrance into an environment closed to all other members 

 of its genus. 



The writer has come across two species of insects, one a 

 dragonfly, the other a mayfly, in which a reversal of one or more 

 of the tropisms normal to the other species of the same genus 

 has permitted the entrance of these reversed species into environ- 

 ments not open to the normal members of the genus. These 

 finds have opened up so many interesting problems in behavior 

 and distribution that they are well worth presenting in some 

 detail. 



* Contribution from the Department of Zoology and Entomology, Ohio State 

 University, number 79. 



