Journal of the New York Entomological Society
The various means by which insects rest have been but little investigated. Occasional notes have been published, but often in connection with other matter, so that it is extremely difficult to collate the recorded facts. Since the Hymenoptera are among the most assiduous, as well as the most intelligent workers, it is natural that they should exhibit some interesting habits of sleep. The idea that the bee sleeps in the flower seems to have invaded literature at an early date. And there are a number of bees that commonly do remain in flowers (such as those of cucurbits and campanulas) all night. Whether this is a natural rest has not, l think, been considered, It may be that the insect remains, because, when ready to depart, it finds that it cannot see. The resting or sleeping habits of ants have been treated by various writers. That certain bees and fossorial Hymenoptera rest under peculiar conditions appears to have been known for many years, but I cannot trace out much literature on the subject. An article by Mr. E. A. Schwarz, referred to below, seems to be the most extensive paper published on this phase of insect sleep.
Banks, Nathan, "Sleeping Habits of Certain Hymenoptera" (1902). An. Paper 203.