164 



ENTOMOLOGY. 



is very broad and flat, with the iuner surface covered with 

 dense stiff hairs, upon which the pollen of flowers is stuck, 

 or piled up, so as to form a yellow heap which is borne to 

 the hive. 



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

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

 innermost pair is barbed at the end. The sting corresponds 

 to the egg-layer or ovipositor of the grasshopper, or of the 

 ichneumon-fly. 



In their mouth-parts Hymenoptera are wonderfully 

 specialized; they can bite, pierce, cut, suck, or lap. They 

 are swift on the wing; their habits are related to their 



Fig. 206.— Digestive canal of the honey-bee. a, salivary glands; b, oesophagus; 

 c. stomach; d, the numerous urinary tubes opening into the intestine, e; /, 

 rectum; g, rectal glands.— After Dufour. 



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 these and other 

 causes the order has flourished to a wonderful degree. 



In this order, says Darwin, "slight differences in color, 

 according to sex, are common, but conspicuous differences 

 are rare except in the family of bees. " In the Ichneumonidae 

 the males are almost always lighter colored than the females; 

 while in the Tenthredinida3 the males are generally darker 

 than the females. In Tremex columba the female is much 

 brighter colored than the male. In the ants the males of- 

 several species are black, the females being testaceous. The 

 sexes of bees often differ in color, the males generally being 



