TYPE TRACHEATA. 513 



longed into a cylindrical snoutlike process at the extremity 

 of which is the mouth, in the Boring-beetles, and in the Po- 

 tato-beetle (Doryphora) it is formed of five joints, one of which 

 is exceedingly small. In other forms, such as Meloe and the 

 Blister-beetles (Lytta), the tarsi of the two anterior pairs of 

 legs are five-jointed and those of the last pair four-jointed, 

 and in others again, such as the Fireflies, the Click-beetles, 

 (Elateridae), the Lamellicornes, the Burying-beetles and 

 Staphylinidae, the Water-beetles (Gyrinus, Hydrophilus, etc.), 

 the Carabidne (Calosoma, Carabus, Harpalus, Bracliinus, etc.), 

 and the Tiger-beetles (Oicindela), all the tarsi are five-jointed, 

 and all the joints approximately equally developed. 



The larvae vary greatly in form in the different genera. 

 In the Lady-bugs and some other forms they are Thysanuri- 

 form, the three anterior trunk-segments (corresponding to the 

 thoracic segments of the imago) possessing each a pair of limbs, 

 while the abdomen terminates in a pair of cerci. In some 

 Water-beetles (Gyrinus] tracheal gills are present, and the 

 larvae of the Lamellicorns (Fig. 239, ) are soft-bodied eyeless 

 white forms, characterized by a saclike dilatation of the last 

 abdominal segment, and live beneath the surface of the 

 ground feeding upon the roots of grasses. In the Click-bee- 

 tles (Elateridse) the body of the larva is elongated and slen- 

 der and very hard, these forms being known as the wire- 

 worms and feeding, like the Lamellicorn larvae, upon the roots 

 of plants. In the Boring-beetles, the larvae, which excavate 

 burrows beneath the bark or in the wood of various trees, 

 have the limbs almost or quite rudimentary, while maggot- 

 like larvae are characteristic of the Weevils. 



The larva, whose life may be prolonged through several 

 years, passes finally into a resting pupa stage of the libera 

 form, resembling in the body form and the mouth-parts the 

 imago which sooner or later issues from it. The metamor- 

 phosis is thus complete. 



In the peculiar Meloid form Sitaris an interesting phenomenon known 

 as hypermetamorpJiosis occurs. The first larva is Thysauuriform, and is 

 parasitic upon the males of certain bees, passing to the female bee during 

 copulation, and then, during the deposition of the ova in the cells filled 

 with honey, the parasite slips upon the egg, which it consumes. It then 



