20() rA:\rrLY i-^-. — nv^i. ...i„.i.. 



(ither iiisectti. but often npon small fishes, and are sometimes very 

 troublesome in artificial fish ponds, where they attack the young 

 and eat ofi' their fins. They also feed upon dead animal matter of 

 anj- kind which fin-ls its way into the water where they live. 



The larvae of the 

 Dytiseidae are also 

 aquatic and carnivo- 

 rous, and are Imown 



Fig. 10.i. Larva of Dytiscid. uifter Corastock.) ^^ . , Water tigers ' " 



(Fig. 105. 1 In form they are elongate, cylindrical or fusiform, 

 with a large oval or rounded and flattened head. The jaws or man- 

 dibles are sickle-shaped and hollow, so that the.y can easily hold 

 and suck the blood or juice from any prey which they may capture. 

 These grubs remain in the water until full grown, when they seek 

 out some convenient place beneath a board, stone or tuft of vegeta- 

 tion where, by the S(|mrming motions of the body, a cell is formed 

 in which they undergo the pupal stage. The length of time neces- 

 sary for this transformation varies greatly ^^'ith the species and the 

 season. 



Nearly 300 species of Dytiseida? are known from the United 

 States. Of tliese 70. representing 24 genera, have been taken in In- 

 diana. The family does not offer that diversity of color, form and 

 sculpture presented liy the Carabid;e and other families of terres- 

 trial beetles, hence the number of cliaractei-s used for the separation 

 of genera and species is limited and the work, therefore, made more 

 difficult for the beginner. The classification is mainly that of Drs. 

 LeConte. Sharp and Horn and ^Ir. Crotch, in the follo\^ing works: 



LrConte. — "Anah-tical Table of the Species of Hydroporus 

 found in the United States, with Descriptions of New Spe- 

 cies." in Proe. Acad. Xat. Sci. Phil., VII, 1S55. 290-299. 



LrC'diitc. — ■■S>iioiisis of the S]ieeies of Cohnnbetes Inhabiting 

 America North of ^lexico." in Proc. .\cad. Nat. Sei. Phil., 

 1S62. 521-523. 



Crotch. — "Revision of the Dytiseida; of the United States." in 

 Trans. Amer. Ent. See. IV 1S73. 3S3-42-4. 



Sharp. — On Aquatic. Carnivorous Coleoptera or D>i:iseid£e, in 

 Trans. Royal Dublin So.\. II. Ser. 2. 1SS2. 179-1003. 



n<>rn. — iliseellaneous Notes and Short Studies of North Amer- 

 ican Coleoptera. in Trans. .Vmev. Knt. Sdc., X. 18S3, 276-284. 



For convenience the family is fii'st divide<l into subfamilies and 

 tribes. 



