CHAPTER XVIII 



Order Hymenoptera : Ants, Bees, Wasps, etc. 



(Gr. i;/ji)Ji/ = a membrane; Trre/ow = a wing). 



A VERY large order of insects which, typically, have two 

 pairs of wings of moderate size — the hind pair being the 

 smaller — and with few or no cross-veins. The mouth-parts 

 are formed for biting hard things as well as for taking up 

 liquid food, so that well-formed mandibles are always 

 present. In the female the abdomen ends in an ovipositor 

 of some sort, or in a sting which is a modified ovipositor, and 

 the ovipositor when not in use, may be either retracted or 

 exposed. The metamorphosis is "complete." 



The head is, in a general way (and the mouth-parts being 

 excepted) a good deal like that of Diptera, and is very mobile. 

 The mandibles are powerful, hinged biting-organs, which fold 

 across the labrum ; the maxillae and labium may form a 

 complicated proboscis. 



The thorax is peculiar in several ways : the pleura of the 

 prothorax are detached from the pronotum and are thrown 

 forward, carrying the front legs with them; the true ist 

 abdominal segment is incorporated with the thorax, so 

 that the apparent ist abdominal segment is really the 2nd 

 segment of the abdomen. In most of the stinging Hymeno- 

 ptera the trochanter of the legs consists, as usual, of a single 

 piece ; but in most of the stingless Hymenoptera the 

 trochanter is divided into two segments. 



The wings of each side are usually yoked together for 

 concerted action by a row of hooked bristles or hairs on the 

 front edge of the hind wing, which, when the wings are 

 expanded, catch a vein or a fold in the hind edge of the 

 front wing. In some females, and in the workers (which 



