OUTLINES OF ENTOMOLOGY. 27 



ing aud sucking, but the upper jaws (mandibles), though large and 

 sharply toothed, are but little used in mastication, but serve instead as 

 tools, of which very skillful and effective use is made in various me- 

 chanical enterprises. The lower jaws (maxillse) and lower lips (labii) are 

 greatly changed from the typical form, to adapt them for taking up liquid 

 nourishment, upon which the perfect insects mainly subsist. The com- 

 pound eyes cover a considerable portion of the head, and are either 

 round, oblong or kidney-shaped (reniform). Upon the top of the head 

 three small simple eyes (ocelli) can in most 8i)ecie8 be plainly seen. The 

 antennae are short and stout or long and slender (filiform), or flail-shaped : 

 i. e., bent in the middle and thickened more or less toward the tips. 



The first joint of the thorax (the pro-thorax) is very narrow and 

 on top crowded down almost or quite out of sight ; but the second 

 and third joints (the meso- thorax and meta-thorax) are large, and to- 

 gether form a compact and nearly globular division of the body. The 

 legs vary considerably in form in the different groups, but are usually 

 long and rather slender, and terminate in five-jointed feet (tarsi). The 

 wings are composed of glassy or mica-like membrane, supported by a 

 few strong veins. In a majority of the species they are quite narrow, 

 the under pair being smaller than the upper, and during flight are 

 attached to the latter by the row of minute hooks which may be seen 

 on their upper (costal) edges, which catch into a ridge made for that 

 purpose on the lower (inner) margin of the upper pair. In a great 

 number of species of Hymenoptera the abdomen swells out in the mid- 

 dle, tapering to a point at the posterior end, and in the opposite 

 -direction to a slender joint, of greater or less length, called the pedicel 

 or petiole, by which it is attached to the thorax. From six to eight 

 rings or segments only can be distinguished in the abdomen. Each of 

 these appears to be composed of two plates, an upper and a lower (a 

 dorsal and a ventral), the former overlapping the latter on the sides. 

 The tip of the abdomen of the female is always modified into an ovi- 

 positor. If this organ is connected with a poison gland and drawn 

 within the body when not in use, it is called a sting; but if it is a con- 

 spicuous appendage and not capable of emitting poison, it is termed a 

 piercer. 



[Figs. 10 and 11,] Tiie larvte of the higher Hymenoptera are, 



for the most part, soft, fleshy, footless grubs, 

 confined during the whole of the growing pe- 

 riod to the cells of wax, paper or mud in which 

 they are hatched. Some species subsist upon 

 food stored in their cells at the time the eggs 

 from which they hatch are laid ; others require 

 Larva and pupa of Wasp. coustaut feeding and care from the mature in- 



