H YMENOP l^ERA. 63 1 



other parasites. A few species are inquilines, but none 

 have been found to be injurious to vegetation. 



Suborder Aculeata (A-cu-le-a'ta). 

 The Stinging Hymenoptcra. 



In the second of the two suborders into which the Hy- 

 menoptera are divided we find at the caudal end of the 

 body of the female a sting connected with a poison gland, 

 the well-known organ of offence of these insects. This is 

 really the same organ as that which we have termed the 

 borer in the first suborder, but its form and use are differ- 

 ent. It should be said, however, that the sting of insects of 

 this suborder is not a simple spear, as often supposed, but 

 is really a compound organ composed of essentially the 

 same parts as the borer described in preceding pages. In 

 some cases the sting is imperfectly developed : thus we find 

 that while certain ants have well-developed stings, others are 

 not able to sting at all. 



In the Aculeata, as already indicated on page 610, the 

 trochanter of the posterior legs consists of a single segment 

 (Fig. 737, a, c). 



In the adult insects of this suborder the abdomen con- 

 sists of six complete segments in the female, and seven in the 

 male. This character is very useful in separating the sexes 

 of these insects.* 



Family PELECINID^E (Pel-e-cin'i-dae). 



The Petechias {Pel-e-ci'nus). 



This family is represented by a single species, Pelecinus 

 polyturator (P. pol-y-tu-ra'tor), which is a very remarkable 

 insect. The females are common where they occur, and 

 are easily recognized by the slender and very long abdomen 

 (Fig. 762). The abdomen of the male is club-shaped, and 



* No account is taken here of the propodeum (see page 602). 



