THE FLOWER AND THE BEE 



both pollen and nectar are abundant and the nectar is con- 

 cealed in floral tubes only 1^ mm. long, while the temperature 

 of the dense clusters, which offer excellent hiding-places, is 

 usually a little above that of the atmosphere, especially at 

 night. The asters, thistles, and sunflowers have longer floral 

 tubes and are visited much less often by beetles. There are a 

 great many flowers, as in the mustard and carrot families, on 

 which only one or two species of Coleoptera have been taken. 



In the flowers enumerated nectar is a more important allure- 

 ment than pollen, which is not produced in large quantities. 

 But many flowers which are totally devoid of nectar are visited 

 by beetles for pollen. The staminate cones of the Scotch pine 

 (Pinus sylvestris) and of the fir attract many beetles, while 

 many may also be swept from grasses where they devour the 

 anthers as well as the pollen. Beetles are likewise common on 

 conspicuous pollen-flowers like the rose, poppy, and St.-John's- 

 wort, and at times entirely strip the rose-bushes of both flowers 

 and leaves. The frequency with which beetles resort to pollen- 

 flowers led Knuth to conclude that they prefer pollen to nec- 

 tar, but if this were universally true, genera feeding on nectar 

 alone, such as Nemognaiha, would never have been developed. 



Beetles are occasionally taken on two-lipped, or bilabiate, 

 flowers with the nectar deeply concealed, where they are 

 either searching for food or their presence is accidental. Al- 

 though the nectar is inaccessible, it is often possible for them 

 to obtain pollen. According to Kerner many small beetles 

 find a refuge in the interior of gentian-flowers, while species 

 of Cetonia remain for several days in the partially expanded 

 flowers of magnolia feeding on the sweet juices and pollen. 

 Carrion-beetles are sometimes found in great numbers in the 

 ill-smelling spathes of the Aroids, and tubular flowers often 

 provide nocturnal lodging for wayfarers of the Coleoptera. 



18^2 



