CLASS-BOOK OF ZOOLOGY. 133 



pillar-hunters, from the fact that they are seen in the 

 morning and evening upon the branches of trees, usefully 

 employed in devouring caterpillars. 



§ 537. The Bombardier-beetle, (Brachinus.) The dif- 

 ferent species of this genus are small, of a reddisn-brown 

 color above, black below, with bluish-black wing-covers. 

 They are found under stones, and get their name from 

 the manner in which they defend themselves — namely, 

 by ejecting a bluish vapor with a tolerably loud report. 



\ 538. The Water-beetles (Dyticus) are of a yellowish- 

 brown color. Some species are as small as a flea, and 

 others an inch and a half in length. All of them live in 

 the water, and feed on other insects. 



\ 539. When this Beetle is about to lay its eggs, it 

 prepares a neat oblong husk or shell, which it covers 

 with a In-own silk. This nest floats like a boat on the 

 water, with the eggs enclosed, until such time as the 

 young larvae are hatched, and able to leap overboard into 

 their native element. 



; 540. The Whirling Water-beetle (Gyrinus) is fre- 

 quently seen in ponds, swimming with surprising rapidity 

 in larger or smaller circles, in company with others. 

 They are of a flat, oval form, of a dark shining lead-color, 

 and not much larger than a fly. 



§ 541. The small cylindrical, yellowish-white eggs of 

 the Whirling Water-beetle are fastened on the leaves of 

 water-plants in four or five rows, twenty together ; from 

 which, after two or three weeks, proceed long and trans- 

 parent larvae, similar in appearance to Centipedes. 



§ 542. The Whirling Water-beetle is distinguished by 

 having four eyes, viz. two above and two beneath the 

 head ; as well as a bladder of air behind, for the purpose 

 of descending and ascending in the water. 



§ 543. The Rover-beetle, (Staphylinus,) like all its kin- 

 dred species, has a soft, flexible body, a large head with 

 crossing jaws, and very short wing-covers, not extending 

 over more than one-third of the hind-part of the body, 

 although its wings are very large. 



§ 544. The size of the Rover-beetle is as various as 

 the species ; some being three-quarters of an inch long, 

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