Guests, Welcome and Unwelcome 203 



merely, though that may be all very well as an addition to 

 its food. 



Many a humming-bird has been starved to death in 

 captivity, owing to the mistaken notion that honey, or 

 sugar-and-water, was all that it needed; whereas these 

 living, flashing jewels possess tongues which are exactly 

 adapted for picking up insects; and insects are their prin- 

 cipal food, though they take nectar as well. 



The humming-bird's tongue is long, and can be 

 stretched out far beyond its bill; it is very flexible, and 

 being cleft in two it can be opened and shut at will, "like 

 a delicate, pliable pair of forceps." 



The humming-bird is, indeed, nearly related to the 

 swift, and its chief diet consists of the small insects, which 

 are seldom wanting in the long-throated blossoms of the 

 tropics. The sheaths of the arums and their kindred are 

 generally full of insects, too; so are those of the palms, 

 and the ** pitchers" with which many plants are furnished 

 likewise afford insects in abundance. 



Whether the birds go for nectar or for insects, it is all 

 the same so far as the plant is concerned, for in neither 

 case can they help coming in contact with the stamens and 

 getting their heads and beaks dusted with pollen. 



Bees, butterflies, moths, birds — these are the most 

 conspicuous of the "under-gardeners" to whom is in- 

 trusted the important work of fertilization; but there are 

 others equally useful in their way, though their sphere of 

 operations is less extensive. Even the wasps do some- 

 thing, for in the absence of fruit they suck flowers, as 

 Gilbert White remarked, especially those of the ivy and 

 small umbelliferous flowers; they are especially attracted 

 by the red and yellow blossoms of the "poker-plant" 



