1908] (jrcgariiis Sleeping Habits among Hymenoptera 127 



Fig. 10. Tenninal portion of the nervous sj^stem of the abdomen, 

 a, b, c, d. nerve-trunks of the terminal ganglion. 

 ad. adipose tissue. 

 con. connective. 

 <?/'. d. ejaculatory duct. 



G7, G8. seventh and eighth abdominal ganglia. 

 h. int. hind intestine. 

 in. n. intestinal nerve. 

 I. lateral nerve-trunk. 



m. n. median nerve. * 



»;.;. bundle of muscles in the eighth abdominal segment. 

 op. opening to the tracheal gills. 

 -V. V. seminal vesicle. 

 tr. trachea. 

 tr. n. tracheal nerve. 

 tv. n. transverse nerve. 

 V. ventral nerve-trunk. 

 V. d. vas deferens. 



A CASE OF GREGARIOUS SLEEPING HABITS AMONG 

 ACULEATE HYMENOPTERA. 



By J. Chester Bradley. 



Mr. Banks* has summarized what was recorded up to the 

 time he wrote concerning the sleeping habits of Hymenoptera. 

 Briefly, this consisted of several observations of usually solitary 

 aculeates either sleeping in flowers or clinging to twigs. Bel- 

 frage has observed Scolia lecontei "during the night and chilly 

 weather in clusters, closely attached to the stems of grass and 

 plants." 



Mr. Banks' observations were made in a small patch of 

 timothy, orchard grass and wild onion. Here he fouiid specimens 

 of three species of Ammophila, of two bees, and of Myzine sex- 

 cincta sleeping, but always only one individual on the same stem 

 of grass. Night after night they would appear between seven and 

 eight, and leave before five the next morning. Gradually they 

 became less numerous. Near the patch was a field of recently 

 cut rye, where he surmises they may previously have rested, 

 and also a garden and bean patch. 



Mr. Schwarzt records observing in southwestern Texas within 

 a short space, four dead shrubs of Celtis pallida which harbored 

 from fifty to seventy specimens of two species of bees asleep, 

 and near at hand other shrubs with a smaller number of specimens. 



* Journ. N. Y. Ent. Soc. Vol. X, p. 209. 

 t Proc. Entom. Soc. Wash., IV, p. 24. 



