888 



AN INTRODUCTION TO ENTOMOLOGY 



The gaster. — The swollen portion of the abdomen behind the pedi- 

 cel in the suborder Clistogastra. 



The pygidial area. — In many of the aculeate or stinging Hymen- 

 opetra there is an area on the pygidivim which is bounded on each 

 side by a carina, the two carinas meeting posteriorly on the middle 

 line of the segment ; this area is known as the pygidial area. 



The anal lobe. — The posterior lobe of the wings, which is defined 

 on page 6i (Fig. 71, /) is also called the anal lobe. In the suborder 

 Clistogastra the presence or absence of an anal lobe in the hind wings 

 is an important taxonomic character. 



The preaxillary excision. — In the hind wings of some H^-menoptera 

 there is in addition to the axillary excision, defined on page 61, an- 

 other notch, the preaxillary excision. In the hind wings of the 

 Hymenoptera the axillary excision, when present, is at the apex of 



ae pae 



Fig. 1 13 1. — Wings of Elis: ae, axillary excision; pae, preaxillary excision. 



the second anal furrow, which lies between the second and the third 

 anal veins (Fig. 1131, ae); the notch may be present in forms in 

 which' both the furrow and the veins are lacking. The preaxillary 

 excision is situated at the apex of the first anal fold, which is just 

 cephalad of the first anal vein (Fig. 1131, pae). 



The preanal lobe.— That portion of the anal area of the hind wings 

 that lies between the axillary excision and the preaxillary excision 

 constitutes the preanal lobe. 



In the Hymenoptera the metamorphosis is complete. The larvae 

 of the Chalastogastra are caterpillar-like in form and are furnished 

 with thoracic legs and usually with abdominal prolegs ; but in some, 

 mostly borers or internal feeders, the prolegs are wanting. In all 



