CLASSIFICATION OF HYMENOPTERA. 159 



the expansion of their wings. The duration of their lives, from 

 the hatching of the egg to the final change, is believed never to 

 exceed a year. 



686. This Order may be primarily divided into two groups, 

 according to the nature of the organ in which the body of the 

 female terminates ; the end of the abdomen being prolonged, in 

 the TEREBRANTIA, into a saw or borer for the deposition of the 

 eggs ; whilst, in the ACULEATA, it is formed into a sting or 

 piercer connected with a poison-reservoir. In the former group, 

 the number of joints in the antennae is extremely variable; 

 whilst in the latter, it is always twelve in the female, and thirteen 

 in the male. The Terebrantia may be again divided into the 

 PHYTIPHAGA, of which the larvae feed upon vegetable matter ; 

 and the ENTOMOPHAGA, in which they generally feed parasiti- 

 cally upon living insects. The Aculeata are in like manner 

 divided into the PR^EDONES, or predaceous tribes, which do not 

 collect pollen, and in which the larvae feed upon other insects 

 stored up for them, or upon fluids stored up by the neuters ; 

 and the MELLIFERA, in which the larvaa feed upon honey or 

 pollen-paste, collected and stored up for them. All these have 

 characteristic distinctions in their adult form ; on which it would 

 not be accordant with the character of this work to dwell 

 minutely. The division of the Order into sections may be better 

 understood from the following tabular arrangement of them : 



I" Larvae vegetdble- 

 Possessiiig ovipositor TEREBRANTIA < feeders I. PHYTIPHAGA. 



[ Larvae parasitic II. ENTOMOPHAGA. 



* -.7 . * fPredaceovinJiabits.III. PR^DONES. 



{ HanwcoUecton IV. MELLIFERA. 



687. Section I. TEREBRANTIA PHYTIPHAGA. The principal 

 family of this section is that of TENTHREDINID^, or Saw-flies, so 

 named from the saw-like character and action of the ovipositor. 

 With this instrument they make a succession of small holes in the 

 branches or other parts of tre^s, into each of which they insert an 

 egg, closing the hole with a drop of frothy fluid. The tissue in 

 the neighbourhood of the wound swells up from its irritation; and 

 sometimes becomes a kind of gall^ either woody or pulpy, accord- 



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