182 Annals Entomological Society of America [Vol. XV, 



This prima facie evidence, brought to my attention by Mr. 

 Flint, led me to make the following observations and experi- 

 ments with the object of proving whether certain species of 

 Tetralonia and Melissodes pollenize red clover or not. In this 

 study I had the assistance of Mr. F. Q. Otanes, a graduate 

 student, who was investigating the general subject of insects in 

 relation to the production of clover seed. The species used 

 in our work were kindly determined by Mr. Henry L. Viereck. 



1. Tetralonia dilecta Cress. = {T. speciosa Rob., not Cress.). 

 May 19, 1921, Tetralonia dilecta was present, though not 

 abundant, in fields of red clover on the University farm, Urbana, 

 Illinois, and was working busily on the blossoms. The pro- 

 boscis, thrust into the flower, was visible through the corolla, 

 and evidently extended to the bottom of the corolla tube. 

 Specimens collected from clover heads, taken to the laboratory 

 and examined under a microscope, showed many pollen grains, 

 especially on the mentum and the branched hairs of the mentum, 

 but also on the maxillae; in fact, pollen grains occurred almost 

 anywhere on the ventral aspect of the mouth parts. These 

 pollen grains were indistinguishable from those of red clover. 



May 24, when the bees were abundant, a root cage with 

 parallel glass sides and a cover of wire screen was taken to the 

 clover field; in it was placed a solid row of clover heads in full 

 bloom, and into the cage were introduced specimens of Tetralonia 

 dilecta. Some of the bees set to work on the blossoms, and 

 their operations were studied under a hand lens. 



It was essential, of course, to determine if seed would be 

 produced by plants upon which Tetralonia had worked, and 

 from which all other insects had been excluded. To this end, 

 red clover plants were taken which bore heads with unopened 

 buds; opened heads having been removed from the plants. 

 These plants were transplanted to a large flower pot covered 

 with a cage of wire screen with a mesh of one millimeter, and 

 placed out of doors. In a day or two some of the heads were 

 in bloom and bees were introduced into the cage. May 26, 

 I put thirty individuals of T. dilecta into the cage ; a few of them 

 were seen to work on the blossoms during the same day; after 

 twenty-four hours, however, all the bees had died. May 31, 

 Mr. Otanes put several more bees into the cage, and some of 

 these also were observed to work on the flowers. The florets 



