COLEOPTERA 



477 



Fig- 555- 



Fig- 554- 



family one of the favorites of students of 

 Coleoptera. Their popular name is sug- 

 gestive of their predacious habits, and of 

 the stripes with which many are marked. 

 They are usually a metallic green or 

 bronze, banded or spotted with yellow. 

 Some are black; and some that live on 

 white sand are grayish white, being ex- 

 actly like the sand in color. Figure 554 

 represents a common species of Cicindela. 

 A useful character for distinguishing the members of this family 

 is the fact that the terminal hook of the maxilla (the digitus) is 

 united to this organ by a movable joint (Fig. 555, h). 



The sexes of the tiger-beetles can be distinguished, except in 

 AmblycJieila, by the sixth abdominal segment of the males being 

 notched so as to expose a small seventh segment; while in the 

 females only six segments are visible. In the males, the first three 

 segments of the anterior tarsi are usually dilated and densely clothed 

 with hair beneath. 



The tiger-beetle larvse (Fig. 556) are as ugly and ungraceful as 

 the adults are beautiful. The two have only one habit in common — 

 their eagerness for prey. The larvae live in vertical 

 burrows in sandy places or in beaten paths. These 

 burrows occur also in ploughed fields that have become 

 dry and hard. The}' often extend a foot or more in depth. 

 The larva takes a position of watchfulness at the 

 mouth of its burrow. Its dirt -colored head is bent at 

 right angles to its lighter-colored body and makes a 

 neat plug to the opening of the hole. Its rapacious jaws 

 extend upward, wide open, ready to seize the first un- 

 wary insect that walks over this living trap, or near it; 

 for a larva will throw its body forward some distance 

 in order to seize its prey. On the fifth t egment of the 

 abdomen there is a hump, and on this hump are two hooks curved 

 forward. This is an arrangement by which the little rascal can hold 

 back and keep from being jerked out of its hole when it gets some 

 large insect by the leg, and by which it can drag its struggling prey 

 down into its lair, where it may eat it at leisure. It is interesting 

 to thrust a straw down into one of these burrows, and then dig it 

 out with a trowel. The chances are that you will find the indignant 

 inhabitant at the remote end of the burrow, chewing savagely at the 

 end of the intruding straw. 



One hundred and fourteen species of tiger-beetles are now listed in 

 our fauna; these represent four genera, which can be separated as 

 follows : 



A. Posterior coxae contiguous; eyes large, prominent. 



B. Third joint of the maxillary palpi shorter than the fourth. . .Cicindela 

 BB. Third joint of the maxillary palpi longer than the fourth Tetracha 



AA. Posterior coxae separated; eyes small. 



Fig. 556. 



