Dec, 1903 ] Brues : Sleeping Harits OK Hymenoptera. L'2i> 



were easily picked off with the forceps before the others became 

 aroused and gradually flew away to seek another resting place. 

 Wasps of both sexes of this single species were represented amoiig the 

 captured individuals. This same species of sweet clover, which is very 

 abundant in northern Illinois and is much sought for by various 

 Aculeata during the day, was the center of the second observation 

 which we had occasion to make in McHenry Co., 111. This time 

 several species were commingled upon the same plants. Among 

 them were Epeohis lunatiis, a parasitic bee ; Scolia bicincta, Nysson 

 pla^i^iatus, a species of TacJiytes and some other smaller wasps. In 

 this case the Epeoliis was the predominating form, at the hour when 

 the plants were examined, which was just about at sundown. 



It may, I think, be properly asked whether the strong scent given 

 off at all times by the clover attracts the insects or whether they 

 simply settle down upon the plants which they have frequented during 

 the busier hours of the day. The fact that the Priononyx are not 

 often seen on this plant in the daytime and the large numbers con- 

 gregated on one bush at night would lead one to believe that they 

 are attracted by the plant's odor as well as by the presence of their 

 fellows which have already settled there. 



Indeed each species usually has its own preference as to sleeping 

 plant. In the case of the Texan Scolia lecontei, this is a species be- 

 longing to the Umbelliferffi. On any warm spring evening shortly 

 after sunset one can col'ect numbers of the male Scolias resting upon 

 or below the older umbels whose inflorescence has passed away. In 

 nearly all cases the wasps rest with the head down ; in this position 

 their bodies harmonize well with the plant and they are not at all 

 conspicuous. Whether this is why the same plant is always chosen 

 would be more difficult to say. As they leave the brilliant red and 

 yellow flowers of LepacJiys coliimnaris severely alone, although resting 

 upon these the similarly colored Scolias would be much more neatly 

 concealed, it seems that concealment cannot be the cause of the 

 choice. 



In the common Myzine sexcincta, another scoliid wasp, gre- 

 garious resting habits can be observed not only late in the evening 

 but in the middle of the day. In southern Illinois one hot day in 

 August I noticed upon a small dried plant of a species of wild pink a 

 large number of the males of the Myzine resting so thickly upon its 

 stem and branches that they gave it a brilliant color with their con- 



