i 3 6 THE STUDY OF INSECTS 



fly well. When approached, they remain still until we can see them well 

 but are still out of reach; then like a flash they fly up and away, alight- 

 ing several rods ahead of us. Before alighting they usually turn so 

 that they face us, and can thus watch our movements. They hide by 

 night and in cloudy or rainy weather in holes in the ground or beneath 

 stones or rubbish. The beetles have been found hibernating, each in a 

 separate burrow extending under a stone. We have seen 

 them in September digging burrows in a hillside; these 

 descended slightly and were about five inches deep. The 

 beetles kicked the dirt out behind them as they dug, so 

 that it lay in a heap at the opening of the hole. 



There are two species of the genus Tetracha (Fig. 223) 

 widely distributed in the United States. The species, Am- 

 blycheila cylindriformis , found from Kansas to New Mexico 

 is a very large one for it is nearly 1? inches long. Over 

 Fig. 22.?. — Tetra- thirty species of the genus ( huus are found along the Pacific 

 coast. These beetles are nocturnal : they search for their 

 prey at night. 



Family CarabievE 

 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, where they hide 

 by day. At night they roam about in search of their prey. Our more 

 common species are easily recognized by their shining black color and 

 long legs. On the Pacific Coast, however, the darkling beetles (Family 

 Tenebrionidae) , which are also black and have long legs, abound under 

 stones and fragments 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 gradu- 

 ally towards the tip, and each segment is of nearly uniform thickness 

 throughout its length; the legs are fitted for running, and the antennas 

 are inserted between the base of the mandibles and the eyes. 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 almost always 

 ornamented with longitudinal ridges and rows of punctures. 



Most members of this family are predacious, feeding upon 

 other insects, which they spring upon or capture by chase. A few 

 species use vegetable food ; but their depredations are rarely of eco- 

 nomic importance. As there are more than two thousand described 

 North American species, and as many of the species are very com- 

 mon, this family may be considered the most important family of 

 the predacious insects. 



The larvae of ground-beetles are generally long, with the body of 

 nearly equal breadth throughout (Fig. 224). They have sharp pro- 

 jecting mandibles ; and the caudal end of the body is usually furnished with 

 a pair of conical bristly appendages. They live in the same obscure situa- 



