330 



THE STUDY OF INSECTS 



This is one of the orders in which in the specialization of the wings 

 the wing-venation is reduced. In the more generalized members of the 

 order this reduction of the wing- venation is slight, but in the more spe- 

 cialized forms it is extreme. 



Figures 572 and 573 represent what may be regarded as a typical 



*d A A/ A 



Fig. 572. — The veins of a typical hymenopterous wing. 



hymenopterous wing; in the former the veins are lettered, in the latter, 

 the cells. 



The cells marked m, m, m, in Figure 573 are termed the marginal cells; 



Fig. 573- — The cells of a typical hymenopterous wing. 



and those marked sm, sm, sm, sm, the submarginal cells; the three cells, 

 M 4 , 1 st M 2 , and M 3 are termed the discal cells. 



The working out of the various ways in which the wing-venation has 

 been reduced in the more specialized families is an exceedingly difficult 

 problem, one that is beyond the scope of this book. 



The mouth-parts are formed for chewing in all Hvmenoptera, and in 

 the more specialized members of the order they are fitted for both chew- 

 ing and for sucking or lapping liquid food. In the sawflies, for example, 

 the mouth-parts resemble quite closely the orthopterous type, while in 

 the bees they differ markedly from this type; and intermediate forms 

 exhibit intermediate degrees of modification of the mouth-parts. 



In the long-tongued bees the labrum and mandibles retain the form 

 characteristic of chewing insects and the mandibles function as organs for 

 crushing or cutting; but the labium and maxillae are elongated; the 

 maxillae form a sheath to the labium; the three organs thus constituting 

 a suctorial apparatus (Fig. 574). In this figure the maxillae are repre- 

 sented separated from the labium. 



