OUTLINES OF ENTOMOLOGY. 51 



in most species they may be completely covered. This wing structure 

 can be most satisfactorily studied in the common May beetle, one of the 

 species which few people have any repugnance in handling. 



The frame-work or body- wall of most beetles is very hard and firm 

 compared to that of many other insects. This is very necessary to pre- 

 serve them from the varied dangers incident to their terrestrial habits. 



The mouth of beetles is considered as presenting the typical form 

 of that important organ. The six principal parts, mandibles, maxillae, 

 labrum and labium, described in chapter III, Pt. 1st (in which see Fig. 3), 

 are always present, together with other appendages of less direct use. 



The eyes are usually prominent and of various forms, round, oblong, 

 kidney-shaped, curved, and in one group of water beetles entirely 

 divided in the middle, so that there would seem to be two on each 

 side. The ocelli are not usually present, though a few species have a 

 single pair, or perhaps only one. 



The antennae present a great variety of forms, some of which are 

 very singular and beautiful, as may be seen by referring to Fig. 4, Pt. 

 1st. They are mostly eleven-jointed. Only the pro-thorax, which is 

 usually very wide, is visible on the back, with the exception of a small 

 wedge-shaped section of the meso-thorax, termed the scutellum. The 

 abdomen joins the thorax by a wide base, and, in a great majority of 

 beetles, is almost, if not entirely covered by the wing cases. Many of 

 the leaf-feeding species and a few of those that are predaceous, fly with 

 great ease and rapidity, but as a rule, the legs are the principal organs 

 of locomotion. They are horny and strong, and of various shapes to 

 adapt them for running, leaping, swimming and other uses. The ap- 

 parent joints of the feet vary in number from three to five, and the foot 

 terminates in most cases in a pair of sharp claws. 



The Iarva3 of beetles are commonly called "grubs." Most of these 

 are soft, clumsy looking objects, with horny heads and three pairs of 

 sprawling legs on the thoracic segments. Some species have in addi- 

 tion a sort of pro-leg at the hinder end of the body, or one or two rows 

 of tubercles (fleshy points) along the sides, or on the upper or under 

 surface, by which they are enabled to move with ease in the situations 

 in which they are found. The larvae of Water-beetles have numerous 

 oar-like processes along the sides and are capable of swimming very 

 rapidly. 



Besides these forms are others which, living enclosed in the fruit or 

 wood upon which they feed, have no use for legs of any kind, and conse- 

 quently do not possess them. Of such are the Gurculios and many 

 kinds of wood-borers. 



