572 TRANS. ST. LOUIS ACAD. SCIENXE. 



Diptera. — Midasidce, (6S) Midas clavatus Dru., h.t. Bombylidce^ 

 (69) Sparnopolius fulvus Wied. Cojiopid(E, (70) Conops xanthopareus 

 Will., p.; (71) Physocephala tibialis Say. Tachim'dce. (72) sp. ; (73) 

 Cistogaster divisa Lw.. t. ; (74) Acroglossa hesperidarum Will. 



Coleoptera. — Latnpyrid(E. (75) Chauliognathus pennsylvanicus DeG., 

 h.c.t., ab. ScarabceidcE. (76) Euphoria sepulchralis F., h.c.t., ab. ; (77) 

 Trichius piger F., h. 



Hemiptera. — Lygceida;, (78) Lj'gceus fasciatus Dall.. h. ; (79) L. tur- 

 cicus F. 



Birds. — Trochtlidce, (80) Trochilus coUibris L., s. : of course it cannot 

 extract the poUinia. 



The flowers are gnawed by two beetles : Tetraopes tetraofhthalmus 

 Forst. and Epicauta vittata F. 



Of the 63 species bearing pollinia oi Asc/cpias incarnata, 60 

 have the corpuscula on the hairs of their legs or on the pulvilli, 

 23 have them on their claws, and 30 have them attached to their 

 tongues. Dead insects of three species (i, 10, 35) were foimd 

 entrapped and killed by flowers. 



Asclepias Cornuti Dec. — Observations on the insect visitors 

 of this plant were made on 34 days, between June 3i and July 23. 

 Among the insects which frequent the flowers there are many 

 which are able to reach the nectar, but which, as a rule, do not 

 extract the pollen at all, or run the risk of becoming hopelessly 

 entangled and of losing their lives in consequence. Although 

 an efficient visitor may sometimes be unable to free itself on ac- 

 count of all of its feet becoming entangled simultaneously, as in 

 the case of the insects mentioned under A. iiicarnata^ it is obvi- 

 ous that the flower can hardly be considered as adapted to insects 

 which often lose their lives in this way. In a similar way all 

 insects should be regarded as intruders which do not readily ex- 

 tract the pollinia, either on account of their small size, or their 

 way of resting upon the flowers. From these considerations I 

 place the visitors in separate groups. 



The following insects were found dead upon the flowers : 



Hymenoptera. — Apidce. (i) Apis mellifica L. g , p.c.t. 



Diptera. — Tachinidce. (2) Acroglossa hesperidarum Will., p. Sarco- 

 phagidcE^ (3) Sarcophaga sp.. p. MuscidcE, (4) Lucilia cornicina F. ; 

 (5) Stomoxys calcitrans L. AtithomyidcE, (6) Anthomyia, sp. 



