118 BRITISH INSECTS 



some 200 species. These are divided into three 

 main groups or sub-families, according to the 

 length and structure of the tongue (hypopharynx). 

 But all bees have certain characters in common which 

 serve to distinguish them from other members of the 

 order Hymenoptera. They are essentially flower- 

 lovers, and feed their young exclusively on nectar and 

 pollen. If we examine a bee's hairs under the micro- 

 scope, we shall find that at least some of them are 

 minutely branched, or plumose. That these special- 

 ized hairs are of great value in entangling and collect- 

 ing pollen cannot be doubted, although this may not 

 be their sole function, seeing that they are possessed, 

 not only by the females and worker, but also by male 

 bees and " cuckoo " bees, neither of which gather 

 pollen. Bees may also be known by the enlargement 

 of the basal joint of each hind tarsus. This joint, 

 which in many instances is as broad as the tibia, is 

 termed the metatarsus or planta. It often plays an 

 important part in the work of pollen-gathering, stiff 

 hairs on its inner surface serving to rake or brush the 

 pollen grains from the hairs of the body. But different 

 kinds of bees collect and carry home their pollen in 

 different ways. Indeed, the appliances and methods 

 are so varied, and in many cases so little under- 

 stood, that they present a wide field for investi- 

 gation and discovery. By far the larger number 

 of our native bees are solitary in their habits. Many 

 make their nests in burrows, either in the ground, in 

 wood, or in the pith of plant-stems. Others take ad- 

 vantage of existing holes and crannies in this respect 

 resembling some of the solitary wasps. The cells 

 which contain the grubs and their supply of food may 

 be mere chambers excavated in the soil. But the 



