XIII 

 HYMENOPTERA 



Bees, Wasps, etc. 

 This is another very large group of insects. The wings 

 are membranous, as the name implies,* but that alone does 

 not distinguish the group. The hind wings are small, and are 

 often attached by a row of hooks on their front margin to 

 the rear of the front wings, so that the two together function 



as one. The veins of the fore wing 

 are bunched at the front margin 

 to stiffen it, and strongly con- 

 joined toward the wing apex in a 

 chitinous thickening (stigma). 

 The mouthparts are of the biting 



Fig. 51. — A saw fly, (from ^ ° 



Ritsema Bos). type, and functional mandibles are 



present throughout the group; but in the bees labium 

 and maxilla are prolonged and combined into a sucking 

 tube that is suited to gathering the nectar of flowers. 

 The antennae are long and often elbowed and reversible. 

 The tarsi are 5-jointed. The end of the abdomen in the 

 female is armed with an ovipositor or a sting. 



The order is remarkable for an extraordinary diversity 

 of habits. The sawflies are herbivorous. A very large portion 

 of the group is of parasitic habits. The wasps are mainly 

 predatory; the ants, omnivorous and social; the bees, mainly 

 social and with a domestic economy that is based on flower 



* hymen, membrane, and pteron, wing. 



124 



