Animals of the Mississippi Bottoms near Quincij. 163 



Family Dytiscid.e. (Predaceous Water Beetles.) 



The larvae of these beetles are known as water-tigers from 

 their rapacious habits. They have smooth bodies and long 

 sickle-shaped jaws. In addition to these characters may be 

 mentioned, as distinguishing these larva3, the laterally placed 

 antennae, 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 

 devouring whatever they can master. They do not hesitate to 

 attack animals many times larger than themselves and are very 

 destructive in fish ponds to young fishes. They are in turn 

 eaten by the larger fishes. They live, in some cases, several 

 years. lu the fall some of the beetles go into the mud to 

 hibernate; others may be seen actively swimming about in mid- 

 winter; and a few leave the water to hibernate under rubbish. 

 The eggs are laid at intervals, and are scattered. Some, at 

 least, of the larva3 become pupa3 in the fall and emerge as adult 

 beetles the following spring. 



Laccophilus niaculosus, Germ. 



(Germar, Ins. Spec. Nov., p. 30 [as cited by G. R. Crotch] ; 

 Say, Compl. Writ, ii, 514.) 



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



Laccophilus fasciatus, Aube. 



(Aube, Species General des Coleopteres, 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. 



{Hi/droporus lacustris, Say, Trans. Am. Philos. Soc, N. 

 Ser., ii, 103, 1825; Compl. Writ., ii, 517,) 



A minute species taken in Willow Slough and Cedar Creek. 

 Hijdroporns aulicus, Aube. 



(Aube, Species General des Coleopteres, vi, 572, 1838 ; 

 Crotch, Trans. Am. Ent. Soc, iv, 396, 1872-73.) 



Not rare in Wood Slough. 

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