2J:^ FAiriLY TI. — HTDROPHILID.?:. 



implies, they are u>xially found in jionds and streams, but are less 

 active swimmers than the majority of the diving beetles. In swim- 

 ming they move the hind l'-?s alternately, while the Djiiseidae strike 

 with them both togetbi-r. like a frog. Several genera are. however, 

 terrestrial in habit, living in moist earth and in the dung of cattle. 

 where they are said to feed upon the larrte of dipiteroas insects. 



The priniipal eharacters of the Hydrophilidae. briefly stated. 

 are a,s follows : -ves large ; mentum lar»". quadrate : antennae with 

 from six to nine joints, the outer ones forming an abrupt club, of 

 which all the joints except the fii-t are puKesr-ut : inserted under 

 the sidles of the front behind t!ie l>ase of tlie mandibles. Thorax 

 with episteriLa and epimera not distinct, the pros-temum very short. 

 S' iireUum always pre'^ent. Metastemum lar^e: frequently earinate 

 aii'I firodiiced into a long spine lif-h.ind. Hind coxae oblique, flat, 

 i^xtendinc to ^idcs nf abdomen, the latter with five visible st-grnent^. 

 Tarsi •")- jointed, the fir-r joint often tcfa- ^niaTl. the middle and hind 

 ones sometinM-s compressed and fring -'1 for -wimming. 



As their common name denot'^^. the water scavenger be-th?-? are 

 ^ufi|iOs.?d to li\'e upon dccomi".^ing aquatic vegetation, but the 

 larvae are earnivorf>ui and often catch and eat living insects and 

 water snails, lliese larvae re>'nible S'lrne^rhat th'ise of the diviiig 

 lieetle-. but the body is more plump and the mandil'les sh"iter and 

 u.saally toothed. The eggs of the larger species are encased by the 

 female in a waterproof receptacle, formed of a silk-like secretion. 

 The,-e egg-cases, which sometim-^s contain 100 or more eggs, are 

 either fastened on the under side of leaves of water plants, or are 

 aEowed to float free. In a few iri^'anees the cases are carried about 

 by the mother on the under side of her horly until the young hat<h. 

 The pupal stage is undcgi^ne on land, in an underground cell or in 

 a canity scooped out beneath S'inie object close to the water "s edge. 



The principal literature treating of the North American species 

 of the family is as follows : 



LfC'or.tf. — ">>T)op^is of the Hydn.pbilidae of the Unit'd 

 Stat^^." r,\ Proe. Phil. Acad. Xat. >.-:., x\\_ 1^5.5 .3.-,e;_:37.5. 



Born. — 'E'^i.-ision of the Genera and Sp^^ci^-^ of the Tribe Hy- 

 drobiini."" in Proc. Xmf-r. Phil. .^oe.. XIII. 1-73. 11^-137. 



Horn. — ^' Synoptic Tables of ^ me 1 i nera of < .If^.pt.-ra," in 

 Traijs. Amer. Entom. S.m?.. V. l-7o. ■2."il. 



Born. — "X..t.'=; on the St ■•- of is. hthebiw of Boreal Amer- 



. iea.'" in Trans. Am. Ent. S. . XVII. 1 -m 17-26. 



