AlV ECONOMIC ENTOiMOLOGY. 



injurious to the agriculturist, the series may be, as a whole, 

 accounted beneficial. 



In the Clavicornia we have a much greater diversity of form, 

 and many families, differing widely in habit, and some of these are 

 economically important. 



Fig. 140. 



A water-scavenger, Hydrophilus triangularis. — a, the larva ; b, male adult ; c, pupa ; d, 

 opened, and e, closed egg case ; y to i, enlarged structural details of the adult. 



First, joining to the aquatic Adephaga there are two families 

 of aquatic Clavicornia, the HydrophilidcB, or "water-scavengers," 

 and the Gyn^inidce, or "whirligig-beetles." 

 The former resemble the water-tigers in 

 general appearance, but are more convex 

 above and more flattened below, usually with 

 brightly-polished wing-covers. The differ- 

 ence in the form of the antennae will easily 

 prevent confusing the families. 



The Gyrinidiz cannot be mistaken. They 

 ^1,,^' " are black or bronzed, oval, shining, with un- 

 usually long forelegs, and disport themselves 

 in swarms on the surface of ponds and streams, 

 darting here and there, or sometimes swim- 

 ming rapidly in large or small, regular or 

 irregular circles, whence they derive their "whirligig" appella- 

 tion. They are predaceous in all stages, but of no agricultural 

 value from their strictly aquatic habits. 



A ■' whirligig"-beetle 

 (1) and its larva (2) : nat- 

 ural size. 



