BEE AND OTHER MEMBRANE-WINQED INSECTS. 127 



The sting, if examined by the microscope, is seen to be 

 formed of three pairs of sharp narrow blades, of which the 

 innermost pair are barbed at 

 the end. The sting corre- 

 sponds to the egg-layer or ovi- 

 positor of the grasshopper, or 

 of the ichneumon-fly. 



In their mouth-parts Hy- 

 menoptera are wonderfully 

 specialized ; they can bite, 

 pierce, cut, suck, or lap. 

 They are swift on the wing ; 

 their habits are related to 

 their great range of station. 

 Their metamorphosis is the 

 most complete of all insects, 

 the young wasps and bees 

 being footless and fed by the 

 parents. From all these and 

 other causes the order has 

 flourished to a wonderful de- 



gree. 



Looking back and over the 

 insect-world, we see what an 

 astonishing variety of insect 

 forms have lived, and still are 

 living, on the earth and in the 

 air. And they all agree, as a 

 rule, 1)1 having jointed bodies 

 and jointed limbs, the seg- 

 ments arranged in three re- 

 gions, most of them having 

 wings, and most transforming 

 from a larva to a pupa, and 

 from a pupa to a perfect in- 

 sect. 



If we judge by numbers alone, the insects are the most 

 successful group of animals ; for there are perhaps 200,000 



Fig. 136.— Nestof Andrena. ^.levdof 

 ^ound; a, flrst-made cell, contain- 

 ing a pupa; b I, larvae: e, poUen 

 mass with an e^ laid on it; /, pollen 

 mass freshly deposited by the bee. 



