y5 



Family Dytiscid.i^.. (Predaceous Water Beetles.) 



Body and legs of the adult beetle generally flattened, suited to- 

 rapid locomotion in the water; antenna* ll-jointed, thread-like, 

 inserted behind the mandibles, under the front. The larv* of these 

 beetles are known as water-tigers from their rapacious habits. 

 They have smooth bodies and long sickle-shaped jaws. In addi- 

 tion to these characters may be mentioned, as distinguishing these- 

 larvae, the laterally placed antenna?, the presence of two claws on 

 the tarsus, and the apparent absence of the 9th segment of the- 

 abdomen. 



Both adults and young lead a predatory life, attacking and de- 

 vouring whatever they can master. They do not hesitate to attack 

 animals many times larger than themselves and are very destruc- 

 tive in fish ponds to young fishes. They are in their turn eaten by 

 the larger fishes. They live, in some cases, several years. In the- 

 fall some of the beetles go into the mud to hibernate; others may 

 be seen actively swimming about in midwinter; and a few leave 

 the water to hibernate under rubbish. The eggs are laid at inter- 

 vals and are scattered. Some, at least, of the larvse become pupse- 

 in the fall, and emerge as adult beetles the following spring. 



Laccophilus maciilosus, Germ. 



(Germar, Ins. Spec. Nov., p. 30 (as cited by G. B. Crotch); Say^ 

 Com pi. Writ, ii, 514.) 



From Cedar Creek, Aug. 8. Apparently not common. 



Laccophilus fasciafus, Aube. 



(Aub6, Species General des Coleop6tres, vi, 423, 1838; Crotch,. 

 Trans. Am. Ent. Soc. iv, 400, 1872-73.) 



This small beetle, generally common in our ponds and lakes, was- 

 seen only in Cedar Creek. 



Bidessus lacustris, Say. 



{Hijclroporns lacusiris, Say, Trans. Am. Philos. Soc, N. Ser., ii,. 

 103, 1825; Com pi. Writ, ii, 517.) 



A minute species taken in Willow Slough and Cedar Creek. 



Hyclroporus aulicus, Aube. 



(Aub6, Species G^n^ral des Col^opt^res, vi, 572, 1838; Crotch,. 

 Trans. Am. Ent. Soc, iv, dm, 1872—73.) 



A handsome beetle about .16 inches long, with bright yellowish, 

 brown head and thorax, and with band of this color on the elytra. 



Not rare in Wood Slough. 



Hydroporus vHiaUpejim's, G. & H. 



{H. Nneafus, LeConte, Proc. Acad. Nat. Sci. Phil., vii, 296, 1885.) 



A small beetle about half as long as the preceding, with wing; 

 covers finely striped longitudinally with black. 



Common in Willow Slouch. 



