1916] The Sleep of Insects 245 ' 



A considerable number of other observations in St. Louis 

 and eastern Kansas find these insects usually coming together 

 in groups of 2 to 50 to sleep, although occasionally solitary 

 individuals are found. In almost every case a dead dark 

 colored weed was sought out and given the preference over the 

 surrounding green vegetation. None have been seen in the 

 vicinity of St. Louis later than about the middle of August, 

 although they have been sought. 



In one case a single bee was found repeatedly snuggHng in 

 the heart of a large group of Priononyx atratum. It came here 

 regularly with the wasps before 5 :30 p. m. 



When the bees were at rest one could see some of them com- 

 pletely covered with yellow pollen. Since about twenty were 

 taken in this condition from sunfloweirs I take this to be sun- 

 flower pollen. Others were dusted with whitish powder, 

 probably snakeroot pollen. One evening I was intensely 

 interested in watching one insect caressing the abdomen of a 

 neighbor with her own. I expected to witness an actual court- 

 ship and copulation, but it soon proved that she was only 

 cleaning the pollen off her own body on to her neighbor. They 

 frequently cleaned themselves before going to sleep. 



The problem of the purpose or cause of some of the insects 

 coming together thus to sleep remains an open question. So 

 far as we can see they could sleep as well on the individual 

 flowers upon which they feed or near their places of nidification. 

 Their persistent choice of the dull, dead plants strongly suggests 

 an element of protection in this selection. Besides the fact that 

 this dull color is in harmony with their own, it may be that their 

 enemies would be less likely to seek for prey upon old dead 

 vegetation than among the green plants which usually harbor 

 insects. But it does seem that the selection of these dark, 

 dried twigs is a conscious choice. 



Melissodes argilis Cress. [J. C. Crawford]. 

 This species of long antennae bee we observed both at St. 

 Louis and Lake View, Kansas. They hied them to the sun- 

 flowers at twiHght and almost always squatted flat in the disk, 

 usually one in each flower. They did not hold on with the 

 mandibles, but I think they sHghtly buried their tarsi in the 

 florets. They seemed to be heavy sleepers and seldom awoke 

 when handled or when the light was flashed upon them. 



