THE FLOWER AND THE BEE 



geranii maculati of the wild geranium {Geranium maculatum)^ 

 Andrena fragariana of the strawberry {Fragaria virginica), 

 and Andrena parnassice of Parnassia caroliniana. It is not so 

 easy to explain the behavior of these latter bees. It seems 

 very remarkable that they should restrict their visits so closely 

 to the flowers mentioned. 



Macropis ciliata, or the loosestrife-bee, usually gets its pollen 

 from the flowers of the common loosestrife {Lysimachia vulgaris) 

 (Fig. 97) ; but it visits other flowers for nectar with which to 

 moisten the pollen, since the loosestrife is nectarless. Many 

 species of Panurginus are taken only on the inflorescence of the 

 ConipositoB. 



But the habit of visiting only one kind of flower is, perhaps, 

 better illustrated by Perdita than by any other genus of bees. 

 This large genus of bees is confined to North America and in- 

 cludes not far from 150 described species and varieties, most 

 common in the arid regions of New Mexico. In Maine 

 Perdita octomaculata is found almost exclusively on the panicles 

 of Solidago juncea, the earliest blooming of the goldenrods 

 (Fig. 56), and only very rarely is met with on any other species 

 of Solidago. In New Mexico two species of Perdita are found 

 on the willows, Perdita zebrata visits only Cleome serrulata, 

 Perdita crotonis visits Croton texensis, Perdita alhipennis visits 

 Helianthus annuus (sunflower), and Perdita senecionis visits 

 Senecio Douglasii. "It may be laid down as a rule," says 

 Cockerell, "that each species of Perdita visits normally but 

 one species of flower, but occasionally specimens may be found 

 on flowers to which normally they do not belong." But in 

 many instances several species of Perdita frequent the same 

 flower. 



Many species of Colletes, Epeolus, and Melissodes visit almost 

 exclusively the flowers of the Compositce, as the thistles, golden- 



112 



