ROBERTSON — FLOWERS .t INSECTS, ASCL. TO SCROPH. 587 



hymenoptera. The foct that they hold a proportion of over one- 

 third in the list of Scrophiilaria is sufficient evidence that the 

 flow^er specially favors wasps. I know of no bee-flower on which 

 so many wasps occur as intruders. On the other hand, it is but 

 natural that bees should intrude in a wasp-flower, since it is fairly 

 impossible to construct a wasp-flower from which bees would be 

 entirely excluded. 



It certainly is not true that the flowers are not easily discovered 

 by bees, and that the nectar is not attractive to them. Some- 

 times hive-bees are present in great numbers, and are about the 

 only visitors to be seen.* Sometimes bumble-bee workers are 

 equally abundant, and no wasps will be observed. On the con- 

 trary, in the latter part of August and first of September, when 

 the number of flowers is reduced, I have found Vcspa maatlata 

 and V. gerjuanica to be the only visitors. This seems to be 

 significant, for, when any flower becomes reduced in numbers, 

 its proper visitors are apt to be the last to leave it. 



The Syrphidce and the Ualichis- females visit the flowers 

 mainly for pollen, and. as Prof. Trelease has observed in the case 

 of the latter, they often pay more attention to the flowers in the 

 male stage ; but the male Halictus and the larger bees visit the 

 flowers for nectar. 



On 15 days, between July I3 and September 19, I observed as 

 visitors : 



Hymenoptera. — Apidvc, (i) Apis mellifica L. ^,s., ab.; (2) Bombus 

 virginicus Oliv, ^ , s. c^ c.p., ab.; (3) B. vagans Sm. (j^ v i (4) ^lelis- 

 sodes bimaculata Lep. c^ 9 ; (5) ; Ceratina dupla Say 9 ? (6) Megachile 

 montivaga Cr. 9 '1 (7) ^I- infragilis Cr. ,^ — all five s. Andre7iidtv, (8) 

 Agapostemon nigricornis F. (^, s. ; (9) Augochlora pura Say ^9) s. & 

 c.p.; (10) Halictus coriaceus Sm. ^9i s. 1^ c.p. ; (ii) H. lerouxii Lep. 

 9,s. &cp.; (12) H. fasciatus Nyl. (J* 9 ? s. & c.p. ; (13) H. zephjrus 

 Sm. fj', s. ; (14) H. confusus Sm. (^^9^ s. <& c.p. Vespidce, (15) Vespa 

 maculata L. ; (16) V. germanica F. ; (17) Polistes rubiginosus Lep. ; 

 (18) P. metricus Say. EumenidK, (19) Zethus spinipes Say; (20) Eu- 

 menes fraternus Say ; (21) Odynerus campestris Sauss. ; (22) O. fora- 

 minatus Sauss. ; (23) O. conformis Sauss.; (24) O. anormis Say; (25) 

 O. pedestris Sauss. ; (26) O. pennsylvanicus Sauss. P/iilanthida', (27) 

 Philanthus punctatus Say. Sphecid(X, (2S) Ammophila vulgaris Cr. — 

 all s. 



* See Farlow in Amer. Jour. Sci. & Arts, 1S71, 3d ser. ii- /51. The plant is, in fact, 

 known in parts of the West as '• Simpson's Bee-plant." 



