518 THE STUDY OF INSECTS. 



Nearly all of our tiger-beetles belong to the genus Cicin- 

 dela (Cic-in-de'la), of which there are about sixty North 

 American species; one of these is 

 represented in Figure 620. We 

 have also two species of TetracJia 

 (Tet'ra-cha) ; see Figure 621. In 

 the Middle West is found Ambly. 

 chila cylindriformis (Am-bly-chi'la 

 cy-lin-dri-for'mis), the giant of the 



FIG. 620. " FIG. 621. ' family, measuring one and three 



eighths inches in length ; and on 



the Pacific coast occur nine species of Omus (O'mus). In 

 this genus the body is smaller and its thorax larger than 

 in Cicindela. These beetles search for their prey only at 

 night. 



Family CARABID.E (Ca-rab'i-dae). 



The Ground-beetles. 



The ground-beetles are so called because they are very 

 common on the surface of the ground, lurking under stones 

 or rubbish, or running through the grass. Our more com- 

 mon species are easily recognized by their shining-black 

 color and long legs. On the Pacific coast, however, the 

 darkling beetles (Family Tenebrioriidae), which are also 

 black and have long legs, abound under stones and frag- 

 ments of wood on the ground. But the two families can be 

 easily distinguished by the fact that in the ground-beetles 

 all the tarsi are five-jointed, while in the darkling beetles the 

 hind tarsi are only four-jointed ; and the darkling beetles do 

 not run rapidly as do the ground-beetles. 



With the ground-beetles the antennae are thread-like, 

 tapering gradually towards the tip, and each segment is of 

 nearly uniform thickness throughout its length ; the legs are 

 fitted for running, and the antennae are inserted on the front 

 above the base of the mandibles. Although most of the 

 species are black, there are those that are blue, green, or 

 brown, and a few that are spotted. The wing-covers are 



