IOWA ACADEMY OF SCIENCES. 99 



Visitors— Hymenoptera—^P»(7«?; Bombus Amerkamta. B. vctffdns, Halictiis 

 coriaceiis, H.fasciatfv, H. tegidaria, Ceratina dvpla. Stelis lateralis, Auf/ochlora 

 piira,Vespi(lu': Odi/iierits forainiuatus. CoiiEOi'TEUA — Capsiihi-: Liiffus prateusis, 

 feeding upon the pollen. DiPTKiix—Surphidn': Plati/cheirus hy/jerhoreus,ieed- 

 ing on pollen. Lepidopteka — Pamphila zabuhm. 



Allium cepa. Flowers in umbels from a one or two-leaved spathe, which soon 

 becomes dry. Flowers with a six parted perianth; segments white, with a single 

 green rib or nerve. Stamens six, style slender with single stigma, which receives 

 pollen from its own and neighboring stamens, but pollination is also often brought 

 about by insects. The insects are attracted by color and the alliaceous odor which 

 is peculiar to the plant. 



Visitors — Hymenoptera — Apidae: Bombus Americanus hurriedly ran over 

 several of the heads. Megachile cent uti culaii s coWected nectar and pollen. Hal- 

 ictus coriaceus, H. gracilis collecting nectar and pollen. Diptera Muscidae 

 Musca domestica. Tachina flavicatilda. Syrphidae: Syrphus fly, with two or 

 three other species, all feeding on pollen and aiding in pollination. 



Asparagus offlcicinatis. L In flower during the latter part of spring and in 

 the early cart of summer, but it also blossoms later in the season in August and 

 September, when it produces but one kind of flower, and consequently no seeds are 

 formed. The flowers are small, green and axillary. Perianth six parted, spread- 

 ing above, six stamens attached to its base, anthers turned inwards, style short, 

 stigma three cleft. Flowers are of two kinds ; that is, it has both staminate and 

 pistillate flowers. Rudimentary stamens are found in the pistillate flowers, and 

 rudimentary pistil in the staminate flowers. Flowers have a pleasant odor, and 

 in spite of their green color they can easily be seen at a distance, the male flower 

 being more conspicuous than tbe female. The insect is first attracted to the male 

 flower, after which it visits the female, and leaves some of the pollen which has 

 adhered to its body, on the pistil; thus the flower is pollinated. 



Visitors — Hymenoptera — Apidae, Megachile centuncularis, Halictus tegu- 

 laris, H. Cressonii, Agaposfemon radiatus, these are all the insects which I was 

 able to secure or took note of. Hermann Mueller gives the following list: Hy'men- 

 OFKTEMK— Apidae: Apis mellifica, Osmia rufa, Prosopis ammilaris, Halictus 

 sexnotatus, collecting pollen and looking here and there in female flowers, and 

 effecting pollination occasionally. 



COMPOSIT.E. 



Helianthus annuus, L. In Compositaj the flowers, being in such close proxi- 

 mity, it is not difficult for poUijaation to take place. The flowers of sunflowers are 

 perfect, but proterandrous. The insect creeps over the head and thus causes 

 pollination. It also, in its efforts to obtain honey, dusts some pollen on its head 

 and thus carries it to another flower. 



Visitors— Hymenoptera Apidce: Apis mellifica collecting pollen and nectar. 

 Megachile centuncularis, collecting pollen. Xomada luteola. Perdita sp. 

 Eucera sp. 



Helianthus tuberosus, L. Visitors— LEPiDiPTERA—CAn/s/)oyAflH?<s thoe. 

 DiPTEUX — Bombylida-: Bombi/ius. Hymenoptera— ^jD/rfrt;.- Xomada luteola, 

 gathering honey. Halictus Leronxii. Melissodes perplexa, gathering pollen 

 and sucking honey. Vespidte: Odyneris foraminatus. 



Sotidago speciosa. Nutt. Visitors— Hymenoptera— ^/;iV7rte: Bombus Vir- 

 ginicus, sucking honey Apis mellifica sucking honey (quite abundant.) Halictus 

 coriaceus, Augochlora pura, Cilissa Americana, Caliopsis Andreniformis. 



