101 



ORDER HYMENOPTERA. 



(Sawflies, Ichneumons, Ants, Wasps, Bees.) 



The word "hyiuenoptera' means ''membranous 

 wings." It is derived from two words, hymen, a 

 membrane and pteron, a wing. Insects of this order 

 have two pairs of membranous wings, which are 

 usually transparent, and at the base of the fore- 

 wings on the second segment of the thorax is a 

 cup-like scale which covers the base of each of the 

 fore wings. This scale is termed a tegula. (Plate 

 21, Figs. 9 and lo.) The veins of the wings are 

 chiefly lengthwise; and with comparatively few 

 cross-veins. These insects can thus be easily dis- 

 tinguished from a typical insect of the Order Neur- 

 optera (lace wings), which have numerous cross- 

 veins forming a distinct lace work. Flies (Order Dip- 

 tera) also have membranous wings and in general, 

 more nearly resemble hymenopterous insects, but 

 flies have but two wings. The hind wings of hymen- 

 opterous insects are smaller than the front pair, 

 and in repose often slip partly under the front 

 wings, so that one needs care in examining some 

 of these insects to separate the two pairs of wings. 

 In flight the hind wings hook on to the front pair 

 by means of a row of curved spines (Plate 14, Fig. 

 5) which are present on the front margin of the 

 hin4 wings. On the back margin of the front 



