40 IOWA ACADEMY OF SCIENCE 



Lepidoptera Eurymus eurytheme (A.) 



Eurymus philodice (A.) 

 Pontia rapae (A.) 

 Autographa brassicae (A.) 

 Anosia plexippus (A.) 



Diptera Exoprosopa sp. (A.) 



Hymenoptera Bombus americana (A.) 



B. bimaculatus (A.) 



B. pennsylvanica (A. C.) 



B. nevadensis (A.) 



B. fervidus (A.) 



B. separatus (A.) 



B. vagans (A.) 



Apis mellifica (A. C.) 



In the above list, the most important pollinators are the bumble- 

 bees of the Hymenoptera and the bumble-bee fly Exoprosopa; these are 

 normal pollinators. The honey bee {Apis mellifica) has been found a 

 good many times. In some cases it visits the flowers for pollen. In 

 such cases the insect lights on the keel, gathers the pollen and makes 

 no effort to get nectar. During the summer of 1910 many bees were 

 found on red clover gathering both nectar and pollen. The nectar was 

 obtained through perforations in the staminal tube. In no case, how- 

 ever, were honey bees observed making these perforations. Pammel in 

 an extended paper on the subject of the perforation of flowers con- 

 cluded that honey bees never perforate flowers. Among the common 

 perforators of flowers the wasp (Vespa) and carpenter bees (Xylocopa) 

 must be mentioned. The Vespa is not infrequent on the flowers of 

 clover and may be responsible for these perforations. 



The Lepidoptera collect only nectar and are by far the most frequent 

 visitors found on the red clover. They are not normal pollinators. 

 Robertson has observed that "these insects cannot depress the keel 

 and though they get a little pollen on the proboscides they are apt to 

 wipe it ofl' by the closely approximated tips of the petal which close 

 the mouth of the flowers." 



Some observations were also made on the number of insects found on 

 the flower of red clover over a given area. Miss Ada Hayden kept a 

 record of these insects found on six feet square for six days, June, 

 1908; Mr. P. Bird for 70 square yards, June, 1909. The species of 

 Bomhiis were not determined as to species but simply listed as Bombus. 



