53 2 THE STUDY OF INSECTS. 



Family STAPHYLINID^E (Staph-y-lin'i-dae). 

 The Rove-beetles. 



The rove-beetles are very common about decaying ani- 

 mal matter, and are often found upon the ground, under 

 stones or other objects. They are mostly very small insects ; 

 a few species, however, are of larger size, measuring a half 

 inch or more in length. Their appearance is very charac- 

 teristic, the body being long and slender, and the wing- 

 covers very short (Fig. 640). The wings, however, 

 are fully developed, often exceeding the abdomen 

 in length ; when not in use the wings are folded 

 beneath the short wing-covers. The abdominal 

 segments are freely movable, and are seven or eight 

 in number. 



It is interesting to watch one of these insects 

 fold its wings ; frequently they find it necessary 

 to make use of the tip of the abdomen or of one of the legs 

 in order to get the wings folded beneath the wing-covers. 



The rove-beetles can run quite swiftly; and they have 

 the curious habit, when disturbed, of raising the tip of the 

 abdomen in a threatening manner, as if they could sting. 

 As some of the larger species resemble wasps somewhat in 

 the form of the body, these threatening motions are often 

 as effective as if the creature really had a sting. 



As these insects feed upon decaying animal and vegetable 

 matter, they should be classed as beneficial. The larvae re- 

 semble the adults in the form of the body and are found in 

 similar situations. 



About one thousand North American species of rove- 

 beetles have been described. The great majority of them 

 are small and exceedingly difficult to determine. Among 

 the large species that are common are the following : 



Creophilus irillosus (Cre-oph/i-lus vil-lo'sus). This species 

 varies from one-half inch to nearly an inch in length. It is 

 of a shining black color, spotted with patches of fine gray 



