1916] , The Sleep of Insects 241 



It was deep twilight a few evenings later when we opened 

 the hole of another and found the owner snug in its burrow, 

 resting as calmly as though it were not expecting intruders 

 at such an hour. 



Odyneris firmus Cress. [S. A. Rohwer.] 



Odyneris geminus Cress. [S. A. Rohwer] 



Odyneris sp. [S. A. Rohwer]. 



The individuals of these species show marked variations in 

 their habits of sleep, sufficient to lead one to suspect that they 

 curl up and sleep wherever it is convenient at the moment of 

 twilight. We have found O. firmus sleeping in its burrow and 

 on vegetation; one was curled around a leaf of Erigeron, and 

 another was in the seed-cluster of a pigweed, in such deep sleep 

 that it unresistingly allowed itself to be picked up repeatedly. 

 O. geminus was found in September, clinging to the Melolotus 

 stalks, and a turret-building Eumenid was sleeping in her 

 finished burrow, beside her egg and its first caterpillar. 



Vespula germanica Fabr. [S. A. Rohwer]. 



At 6:10 a. m., on August 18, this Vespa was just beginning 

 to wake up and stretch itself under a green curled leaf of Hibiscus. 



Polistes. 



When one comes upon a paper nest of Polistes at night he 

 finds the inhabitants quietly at rest, their bodies and legs 

 spread fiat against the surface of the nest. I believe they are 

 fully asleep; one may hold a strong light near them for several 

 minutes before they show the slightest response. 



Despite the fact that the nests are filled with sleeping 

 wasps, one occasionally finds solitary stragglers asleep among 

 the vegetation. They are often seen foraging or getting nectar 

 when it is almost dark, and it is probable that these are overtaken 

 by night w^hile away from home. During the summer probably 

 twenty individuals in all were seen asleep on the flowers of 

 snakeroot, ragweed and sweet clover. The species were 

 P. pallipes, riibrigenosus, aurifer, annularis, variatus and prob- 

 ably bellicosus. They are up and busy early in the morning; a 

 P. aurifer came to a pond for water at 6:15 one August morning, 

 and a P. pallipes was flying from plant to plant at 6 :30. 



