In My Vicarage Garden 



combined. It may be that they are attracted 

 first by sight, for it has been often noted that a 

 large proportion of the flowers visited by night 

 moths are white, but when so attracted it would 

 seem that their sense of smell tells them whether 

 the flower is good for them, and indeed whether it 

 is the very flower they are seeking for. For all 

 insects seem to have their own special flowers, 

 and all flowers their own special insects. There 

 are, of course, cases of flowers being attractive to 

 more than one family of insects, and there are 

 insects, such as bees, which do not confine them- 

 selves to one flower only; but they all work within 

 certain fixed limits, and there are cases when, if 

 the particular insect does not come, the flower 

 cannot perfect itself. The common red clover 

 is a well-known case in point, which so much 

 requires the help of humble-bees and no other 

 bee can help it that Darwin believed that if 

 humble-bees became extinct in England the red 

 clover would wholly disappear ; and in New 

 Zealand it was necessary to ship a large quantity 

 of humble-bees from England before the red clover 

 produced any seed. A less known and almost 

 more curious instance occurs in the yucca, which 

 in Texas is fertilised by the small moth pronuba 

 yuccassella. In England the yucca at night is much 

 more attractive than by day ; the flowers, which are 

 bell-shaped by day, open and become bright stars by 

 night, and the delicate scent is more perceptible ; 

 but all the attractions are in vain, \hzpronuba is not 

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