ROBERTSON FLOWERS A INSECTS. ASCI.. TO SCROPH. 575 



The following- insects either do not extract the pollinia at all, 

 or could not be expected to do so often : 



lljmenoptera. — Afidd'. (17) CeratinaduplaSay ; (18) Megacbile rela- 

 tiva Cr. 9-P-c-, one; (19) Coelioxys S-dentata Say (J' 9 • Andrenidce, 

 (20) Augochlora pura Say % 9 '1 (21) A. labrosa Say ,^9 '1 (22) A. luci- 

 dulaSm. 9 i (23) Sphecodes arvensis Patton. Eume.nidce, (24) Odynerus 

 arvensis Sauss. CrabronidcB. (25) Crabro rufifemur Pack... one. Philan- 

 ikt'dce, (26) Cerceris clypeata Dahlb. LarridK, (27) Lyroda subita Say. 

 Scoliidce, (28) Myzine sexcincta F. Ichneumontdw, (29) Ichneumon 

 flavizonatus Cr.. one, with corpusculum on antenna! 



Diptera. — Syrphidiv, (30) Tropidia quadrata Say. Tachmidcv, (31) 

 Micropalpus sp. ; (32) Frontina sp. 



Lepidoptera. — RJiopalocera, (33) Phyciodes tharos Dru.; (34) Thecla 

 humuli Ilarr.; (35) T. titus F., h.. one; (36) Chrysophanus thoe. Bd.- 

 Lec. ; (37) Lycttna comyntas Godt. ; (38) Pamphila cernes Bd.-Lec. 

 ^'^geriadce, (39) yEgeria remula Hy. Edw. 



The following visitors seem to me to be the only ones adapted 

 to the flower : 



Hymenoptera. — Apida\ (40) Bombus separatus Cr. 9^)''P-c. ; (41) 

 B. pennsylvanicus DeG. %, 5, sp., p.c. t. ; (42) B. scutellaris Cr. ^. 

 BembecidtK^ (43) Bembex nubillipennis Cr., c. Spkecidce, (44) PelopcEus 

 cementarius Dru., c. ; (45) Priononyx thomse F., h. 



Lepidoptera. — R/iopalocera, (46) Papilio asterias F., c. ; (47) Colias 

 philodice Godt.. c. : (48) Danais archippus F., sp.. h.c. ; (49) Argynnis 

 cybele F. ; (50) Pyrameis atalanta, L. 



Finally, the structure of the hoods seem to indicate an adaptation to 

 bumble-bees, and I suspect that before the appearance of the hive-bee the 

 flowers depended mainly upon Bombus separatus. 



I have also seen the flowers visited by the ruby-throated hummino-- 

 bird. Podisus spinosus Dall. frequents the flowers to prey upon entan^rled 

 insects. 



Of the 22 species of insects bearing corpuscula of this Ascle- 

 pias., iS have the corpuscula attached to their claws, 4 have them 

 on the hairs of their legs, 5 have them on their pulvilli, 3 bear 

 them on their tibial spurs, 2 have corpuscula on their tongues, 

 and I, by accident, has a corpusculum attached to the tip of its 

 antenna. 



Asclcpias tiibcrosa L. — The following visitors were taken on 

 this butterfly flower : 



Lepidoptera. — R/topaloceru, (i) Papilio'philenor L.. h. ; (2) P. aste- 



