THE WATER SCAVENGER BEETLES. 



255 



490 (1585). HYDROPHILUS OVATUS Zieg., Proc. Phil. Acacl. Nat. Sci., II, 



1844, 45. 



Less elongate, more convex. Above black with an olive tinge ; beneath 

 piceous ; antenna and tarsi paler. Abdomen pubescent, the last three seg- 

 ments narrowly smooth at middle, without yellow spots at sides. Pro- 

 sternal prominence, in which front end of sternal spine fits, open in front. 

 Length 31-33 mm. 



Southern half of State ; frequent. May 25-October 8. Often at- 

 tracted by electric light. 



491 (1586). HYDROPHILUS TRIANGULARIS 



Say, Journ. Phil. Acacl. 



Nat. Sci., III. 1823, 201 ; 



ibid. II, 128. 



More elongate, less convex. Above of 

 same hue as oratiis; beneath darker, 

 more shining, the abdominal segments 

 with more or less distinct triangular 

 yellow spots at sides. First segment pu- 

 bescent, the remainder broadly smooth 

 at middle. Prostemal prominence closed 

 in front. Length 34-37 mm. ( Fig. 1 20. ) 



Throughout the State ; common. 

 March 19-October 27. Sometimes 



attracted bv thousands to electric Fig. 126. b H. triangdaris Say natural size; 



/, antenna; g, front tarsus of female; , same of 



lights in Indianapolis and the male . ali magnified; i, side view of sternal spine. 



(After Riley.) 



larger cities. Hibernates as imago. 



VI. TROPISTERNUS Sol. 1834. (Gr., "keel 4 breast.") 



Smooth, shining, oval insects, mostly black above; very common 

 in ponds, lakes and slow-flowing streams. Nine species, including 

 Nos. 1588 to 1595 of the Henshaw "Catalogue." belong to this 

 genus, five of which have been taken in Indiana. 



KEY TO INDIANA SPECIES OF TROPISTERNUS. 



a. Prosternal prominence or groove closed in front ; elytra without yellow 



stripes. 

 l>. Thorax and elytra narrowly margined with yellow. 



492. NIMHATI S. 



66. Thorax and elytra entirely black above. 



c. Front part of sternal crest very finely and indistinctly punctured; 

 elytra with very fine and coarser punctures intermixed. 



493. MIXTUS. 

 cc. Front part nf sternal crest distinctly punctured; elytra 1 punctures 



equal in size or nearly so. 



(L Form elongate-oval: elytra 1 punctures very minute and indis 

 tinct. 494. STUL.EVIS. 



[1723402] 



