THEIR RELATION TO PLANTS 25 



and for every species of Yucca there is a species of Pro- 

 nuha. Surely a most wonderful adaptation of insect and 

 plant, neither of which can now exist without the other. 



And yet, while the adaptation is not so specific, nor 

 the evidence of design so apparent, the dependence of 

 red clover upon long-tongued bees is not less absolute. 

 Australia has no native bumble-bee, and red clover was 

 unknown there until the colonists began to cultivate it. 

 There was no difficulty in making crops of forage; but 

 it would not seed. Importing seed annually was expen- 

 sive and, naturally, the Australians were anxious to 

 raise their own. This led to a study of the reasons for 

 the failure, in the course of which the dependence of the 

 plant upon bumble-bees was established. The remedy 

 was obvious, and now European bumble-bees disport 

 themselves among the Australian red clover, seed is 

 plentiful, and interference with bumble-bees is a crime — 

 as it should be rated everywhere. 



Bees, by the way, are the most universal pollenizers, 

 and are highly specialized for that purpose. All bees 

 are more or less hairy: sometimes conspicuously so, a 

 dense woolly clothing appearing all over the body; 

 sometimes sparsely, the hair being often localized. But 

 whatever the bee, and however scant its clothing, the 

 hair is always compound: spurred, branched or even 

 plumose. In some series it is so strikingly characteristic, 

 that from the hair alone, the genus to which a bee 

 belongs can be determined with reasonable certainty. 

 In all modifications and adaptations, be they small or 

 great, the pollen-gathering function is always attained: 

 for bees need pollen in their domestic economy. Most 

 insect mothers have no more care for their offspring 

 than to place the egg in some position where the larva, 

 when hatched, will find food. In the Hymenoptera, to 

 which the bees belong, storing food upon which the 



