i 9 8 THE POPULAR SCIENCE MONTHLY 



out by many bees, flies and butterflies. Bumblebees especially delight 

 in these blossoms, which they visit with astonishing rapidity — Bombus 

 consimilis making about seventy visits per minute. On the middle lobe 

 of the upper lip there are two bright yellow spots, which tell of the 

 presence and guide to the exact location of the nectar concealed within 

 the tube of the perianth. When the pickerel-weed bee makes its appear- 

 ance about the middle of July, there is no other flower in southern 

 Maine which can offer it so many inducements as the pickerel-weed. 

 But let us look farther and see if there are any other bees, which behave 

 in a similar manner. 



In the quiet bays of the river, floating upon the surface of the 

 water, bloom the yellow water lilies (Nymphcea advena). 



Again the wild cow-lily floats 

 Her golden-freighted, tented boats, 

 O 'ershadowed by the whispering reed, 

 And purple plumes of pickerel-weed. 



The flower is securely anchored to the bottom of the stream by a 

 long stem. At first the opening in the bud is no larger than a bee's 

 body, and the chamber within offers a dry and snug shelter amid the 

 waves. It may truly be called a haven of refuge. Directly below the 

 entrance is a broad, many-rayed, crown-shaped stigma, as in the poppy. 

 The petals are thick, wedge-shaped bodies which are orange-yellow on 

 the outer side near the top, where they freely secrete nectar. Under a 

 microscope both large and minute drops can readily be seen. The 

 stamens are indefinite in number; and reveling in the pollen, their 

 bodies completely covered, there is a large and lively company of small 

 flies called Hilara atra. Less common are two beetles, Donacia pisca- 

 trix and Donacia rvfa; but what chiefly interests us is a small bee, 

 Halictus nelumbonis, or the water-lily bee. This bee in this locality is 

 never found on any other flower, but elsewhere it is met with on other 

 species of the water-lily family, or Nymphseaceas. It is an oligotropic 

 bee, and the only species of the great genus Halictus that is known to 

 behave in this way. 



But in Andrena this is a common phenomenon, for instance, in 

 Washington County, Wisconsin, according to Dr. Graenicher, twenty- 

 four of the forty-seven indigenous species of Andrena are oligotropic. 

 This is the largest genus of North American bees. They are sometimes 

 called ground-bees, since they build branched tunnels eight to ten 

 inches deep in the soil of sandy pastures and hillsides. A part of the 

 species are vernal or fly in springtime, while a part are autumnal and 

 fly only in autumn. They provision their cells with balls of " bee- 

 bread," about the size of a garden-pea, composed of pollen moistened 

 with nectar. An egg is laid on the top of the mass of bee-bread, and 

 the cell is then closed. 



The bright yellow staminate aments of the pussy-willow (Salix 



