ANNALS 



The Entomological Society of America 



Volume IX SEPTEMBER, 19 16 Number 3 



THE SLEEP OF INSECTS; AN ECOLOGICAL STUDY. 



By Phil Rau and Nellie Rau, 



St. Louis, Mo. 



An object in motion always attracts the attention of children, 

 young and old; a butterfly flitting from blossom to blossom, a 

 locust jumping before one in the dusty road, a bee rummaging 

 in a flower, all arouse one's interest. But naturalists, like chil- 

 dren, cease to pay attention to insects when the latter cease 

 their activity. Thus the interesting problem of when, where 

 and how insects sleep has been all but neglected. 



The claim of this problem upon our attention is undeniable 

 when we consider the importance of the period of recuperation 

 in the life of all of the members of the organic world. The 

 sleep of plants, or even the sleep of cotyledons, has been made 

 into charming classics by Darwin and others; how much more 

 interesting ought to be the sleep of animate objects. 



The records of this phase of insect life are meagre and 

 isolated, and are only incidental observations. The only 

 purposeful study on the sleep of insects has been done by 

 Fiebrig. This excellent paper is unique in that it deals with the 

 physiological condition of insects during sleep, whereas the 

 other observations and the present study are of an ecological 

 nature. 



Our observations were made entirely in the field, sometimes- 

 after dark with an acetylene lamp, but more frequently between 

 twilight and darkness. The latter method yielded the more 

 attractive results since the behavior could be noted when they 



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