1916] The Sleep of Insects 251 



at the lights, and the females in cages are able to capture prey 

 in the dark. They also construct their egg cases after dark, 

 and some of them remain in copulo during the night. These 

 activities were observed during the daytime also. It may be 

 possible that they snatch a little nap between activities whenever 

 opportunity offers. 



Amblycorypha oblongifolia DeG. [A. N. Caudell]. 



Perhaps a dozen of these green katy-did nymphs were seen 

 at rest on the poison ivy, which at that time, mid-June, was 

 tender and bore green berries. Five of these were actually 

 eating the Rhus. Three others were at rest on pokeberry 

 plants near by. 



Orchelimum nigripes vScud. [A. N. Caudell]. 



This brown and green hopper was found at rest on the vege- 

 tation by 8:30 on different evenings in mid-August, but they 

 were probably awake or sleeping only lightly for occasionally 

 they would move slightly, and one which was picked up bit me 

 so severely that I flung it away in astonishment and it escaped. 



BUTTERFLIES. 

 Pieris protodice [H. Schwarz]. 



A stretch of vacant land in St. Louis about the size of two 

 city blocks bore a good many patches of the white snakeroot, 

 Eupatorium ageroides Linn. At the time when these observa- 

 tions were made the plants had gone to seed, arid instead of the 

 pure white flowers at the apex of each stalk was a fluffy mass of 

 awned seed ready to be puffed away by the wind. These gray- 

 white, feathery tufts seemed to be the favorite resting place of 

 P. protodice for the period from October 6 to 18. 



When walking through the field at deep twilight I saw a 

 number of white spots on top of the grayish heads of this plant, 

 very conspicuous indeed. In this one patch of about twenty- 

 five square yards I counted thirteen of these butterfiies, but 

 on the other plants near by, such as sweet clover and yellow 

 daisy, none were sleeping. 



It was noticeable that they all thus chose the same kind of 

 plant, but more remarkable was the fact that every one of these 

 butterflies rested horizontally on top of the seed mass with the 



