238 Annals Entomological Society of America [Vol. IX, 



chosen plants of the same species and equal desirability very 

 near for independent sleeping quarters if they had been so 

 inclined. 



In another clump of the same plant a short distance away, 

 three wasps were asleep in the same huddled condition, and on 

 the identical part of one plant, cHnging to the stems with the 

 legs instead of the mandibles, as do some other species of wasps. 

 On another scattered group of Erigeron not far away, four of 

 these insects were asleep on the tops of four distinct stalks. 



At the same hour of the morning three days later I examined 

 a patch of Erigeron in another location and found that the 

 wasps rested in the same manner very near to the top of the 

 plants. Five of these plants harbored one each, and five others 

 bore from two to eight. In every case they were crowded 

 together near the top. The sex was ascertained for 24 of the 

 last lot; they were exactly equal, 12 males and 12 females. 

 Early in the evening they were alert and easily alarmed, but by 

 ten o'clock they could be approached with a strong Hght, or the 

 stalk upon which they rested could be stirred without arousing 

 any response in the wasps. Even the strong light and warmth 

 from the carbide lamp held for several minutes within five 

 inches of them did not arouse them or delude them with the 

 idea that daylight had come. 



Records of about fifty other individuals of this species, at 

 different times and places, show conduct as varied as this; 

 about half of them slept alone, near the head of ironweed, white 

 snakeroot and similar weeds, while the others spent the night 

 in groups of from two to eight, or in one case as many as sixteen. 

 Thus the gregarious tendency is sometimes, although not 

 always, present. In only one instance am I positive that a 

 certain individual came back a second night to sleep on its own 

 particular twig, but the habit of returning night after night each 

 to its chosen spot may be common among them. It would be 

 of interest to ascertain whether this is a fixed habit among them, 

 or only a trait appearing occasionally, a habit developing or 

 declining. 



I could ascertain no conditions deciding the question of 

 whether they would sleep singly or in the company of others. 

 Both sexes were present, but I have never observed mating in 

 these night assemblies; the only instance of mating that I have 

 witnessed in this species occurred during the day. I do not see 



