COLEOPTERA 489 



They are mostly very small insects; a few species, however, are of 

 larger size, measuring 12 mm. or more in length. Their appearance 

 is very characteristic, the body being long and slender, 

 and the wing-covers very short (Fig. 577). The wings, 

 however, are fully developed, often exceeding the ab- 

 domen in length; when not in use the wings are folded 

 beneath the short wing-covers. The abdominal seg- 

 ments are freely movable. 



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. Fig. 577. 



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 creatures 

 really had a sting. William Beebe states {Atlantic Monthly, October 

 19 19) that when some rove-beetles were attacked by ants they raised 

 their tails and ejected a drop or two of a repellent fluid which drove 

 the ants away. This observation indicates the probable explanation 

 of the actions of these beetles when disturbed. 



As these insects feed upon decaying animal and vegetable matter, 

 they should be classed as beneficial. The larvcc resemble the adults 

 in the form of the body and are found in similar situations, about 

 decaying animal and vegetable matter, beneath bark and in fungi. 

 Some species are guests in the nests of ants, and others in the nests 

 of termites. 



Nearly three thousand North American species of rove-beetles 

 have been described. The great majority are small and exceedingly 

 difficult to determine. Among the large species that are common are 

 the following. 



Creophilus maxillosus. — This species varies from 12 mm. to nearly 

 25 mm. in length. It is of a shining black color, spotted with patches 

 of fine gray hairs. There is a conspicuous band of these across the 

 middle of the wing-covers, and another on the second and third 

 abominal segments; this abdominal band is best marked on the lower 

 side of the body. 



Staphylinus maculosus is a larger species, which often measures 

 fully 25 mm. in length. It is densely punctured, and of a dull brown 

 color, with the scutellvim black, and a row of obscure, square, blackish 

 spots along the middle of the abdomen. 



Staphylinus vulplnus resembles the preceding somewhat, but it 

 has a pair of bright yellow spots at the base of each abdominal segment. 



Ontholestes cinguldtus is of about the same size as the preceding. 

 It is brown, speckled with brownish black spots, and the tip of its 

 abdomen is clothed with golden hairs. 



The family PSELAPHID^E includes certain very small beetles, 

 the larger ones not exceeding 3 mm. in length. They resemble rove- 



