Guests Welcome and Unwelcome 241 



It is, of course, not to the plant's interest that its 

 pollen and nectar should be taken by insects which 

 plunder without making payment in return, as it is 

 thereby robbed of its means of attracting other and 

 more useful insects. But the useless ones are just as 

 fond of nectar as the useful, just as quick, too, to find 

 it out, wherever it may be hidden, so that many devices 

 are needed to baffle these unwelcome guests. 



Human beings can, it is said, detect less than the 

 twenty-millionth part of a grain of musk ; but in keen- 

 ness of scent they are far surpassed by the insect world. 



Where is the man who can detect any difference, 

 by smell or otherwise, between cane-sugar and beet- 

 sugar, when the latter is properly refined? — not, of 

 course, such as one meets with in continental hotels. 

 Yet the bees know well, for if the choice be given 

 them, they will take the cane and leave the beet. 



And ants are not only as fond of sweets as bees, 

 but will find them out from an immense distance. 

 They have been known to make their way up from the 

 garden to the second story of a house, by means of 

 an outside bell-wire, all for the sake of some dried 

 fruit which they had scented out. They are sure, 

 therefore, to know where nectar may be had, as well 

 as the bees themselves ; and yet, what with their 

 crawling, and their tidy habit of constantly cleaning 

 themselves, and their hard coats, which are not suited 

 for carrying pollen, they are some of the least welcome 

 guests that a flower can have. 



When the ants do get a chance, they make the 

 most of it, and swarm in greedily ; but on the whole 

 they are pretty well kept out, now by one means, now 

 by another. 



16 



