Guests Welcome and Unwelcome 231 



and the butterflies would not rise high enough to find 

 them. 



Under these circumstances, therefore, many trees, 

 such as the custard-apple, bear their blossom on the, 

 trunks or larger branches, where moths and butterflies 

 can find them. The cacao is another which does so, 

 and when the large yellow fruit is ripe, the trunks of 

 some of the smaller trees are hardly to be seen, so 

 thickly does it cover them. 



But, much as these insects do both in the tropics 

 and in the mountains, it must not 

 be supposed that their services could 

 be dispensed with even in temperate 

 latitudes and in the plains. Quite 

 the contrary. Most of the European 

 orchids are fertilized by bees, but 

 just a few species cannot get on 

 without the help of moths. There 

 is a large sphinx-moth which carries 

 pollen to and from one species of 

 orchid in a very curious way — on its 

 eyes. The pollen of this flower 

 grows in two masses, each perched 

 upon a stalk which passes through its centre, and to 

 which the grains are united. At the base of the stalks 

 are tiny button-shaped discs, one on each side of the 

 stigma, face to face. When the moth presses its head 

 into the centre of the flower, the discs come into 

 contact with its eyes, and, being very sticky, they 

 adhere so firmly that the whole thing is dragged out 

 — stalk, pollen, and all. A very strange object one of 

 these moths is when it is thus adorned, for the stalks, 

 with their lumps of pollen at the end, at first stand out 



Pollen mass of an 

 orchid, magnified. 



