326 



Leech and Chandler: Coleoptera 



Fig. 13:20, Hydrocanthus tricolor, ventral surface of 

 adult (Young, 1954). 



3rd antennal segment more than twice as long as 4th 



Hydrocanthus Say 1823 



Mandibles stout, bifid at tip; 3rd antennal segment no 

 longer than 4th Suphisellus Crotch 1873 



Genus Suphisellus Crotch 



Two species, 5. levis (Fall) and S. lineatus (Horn), 

 have been recorded from Baja California. The former 

 is known only by the type from San Jose" del Cabo; 

 the latter has been taken in Texas, and may possibly 

 occur in southeastern California. 



Oval, 3 mm. long; pronotum reddish-yellow, piceous or 

 black discally; elytra reddish-yellow, each elytron with 

 a sutural, discal, humeral, and submarginal black vitta 

 lineatus (Horn) 1 87 1 



Genus Hydrocanthus Say 



In 1928 Zimmermann described H. similator from 

 "Nordamerika: Mass.; Californien." No other Cali- 

 fornia specimens are known, so there is a possibility 

 that his example was mislabeled. On the other hand 

 Horn (1894) listed the eastern H. tricolor Say from 

 Santa Anita, Baja California, and since Zimmermann 

 describes H. similator as like H. iricolor in form and 

 size, there may be a species of Hydrocanthus in 

 California. 



Length 5 mm. Color yellowish-red, elytra scarcely darker 

 than head and pronotum; presternum virtually impunctate, 

 except sometimes on sides of process; metasternum and 

 hind coxal processes densely, strongly punctate, the 

 former smooth at middle just behind anterior margin ("Cal- 

 ifornien") similator Zimmermann 1928 



REFERENCES 



BALFOUR -BROWNE, P., and J. BALFOUR -BROWNE 



1940. An outline of the habits of the water-beetle, 



Noterus capricornis Herbst (Coleopt.). Proc. Roy. 



Ent. Soc. London (A), 15:105-112, 4 comp'd. text 



figs., pi. I. 

 BERTRAM), H. 



1927. Les larves des Dytiscides, Ilygrobiides, Hal- 

 iplides. Universite de Paris. XV+370 pp., 33 pis., 208 

 text figs., + 3 pp. errata et addenda. 



BOVING, A. G., and F. C. CRAIGHEAD 



1931. An illustrated synopsis of the principal larval 

 forms of the order Coleoptera. Ent. Amer., 11 NS. 

 1-351, incl. 125 pis. 

 JACKSON, DOROTHY J. 



1950. Noterus clavicornis Degeer and N. capricornis 

 Herbst (Col., Dytiscidae) in Fife. Ent. Mon. Mag., 

 86:39-43, 2 text figs. 

 MEINERT, FR. 



1901. Vandkalvelarverne (Larvae Dytiscidarum). Det 

 kongelige Danske Videnskabernes Selskabs, Skrifter, 

 (Series 6, Naturvidenskabelig og mathematik) Afdeling, 

 9:341-440, pis. I-VI. 

 REGIMBART, M. 



1878. Etude sur la Classification des Dytiscidae. Ann. 

 Soc. Ent. France, (5), 8:447-466, pi. #10. 

 YOUNG, F. N. 



1954. The water beetles of Florida. Univ. Florida Stud., 

 Biol. Sci. Ser., 5:IX+238 pp., 31 figs. 

 ZIMMERMANN, A. 



1928. Neuer Beitrag zur Kenntnis der Schwimmkafer. 

 Weiner Ent. Zeit., 44:165-187. 



Family GYRINIDAE 



Whirligig Beetles 





Commonly known as whirligig and waltzing beetles 

 and scuttle bugs, the gyrinids (fig. 13:22a, b, c) live up 

 to their names as they actively whirl and gyrate on 

 the surface of the water. They have other vernacular 

 names such as "apple smeller" and "mellow bugs," 

 descriptive of the odors of a milky fluid excreted 

 chiefly in the region of the prothorax. The adults 

 dive readily, and can take flight after climbing out 

 of the water. They are the only aquatic beetles which 

 regularly take advantage of the surface film for sup- 

 port. 8 Although the undersurface is wettable and 

 breaks through the film, the sides of the beetle are 

 supported as is shown by their virtual inability to 

 keep afloat when the surface tension is reduced by 

 the addition of a detergent. The compound eyes are 

 specially adapted for surface life; each eye is divided 

 into two widely separated parts (fig. 13:23), the lower 

 being beneath the surface film as the beetle swims, 



"The species of Hydraenidae, Spercheidae, and various small 

 Hydrophilidae can break through the surface film from below with 

 their tarsal claws. They thus gain traction and support and can 

 walk along upside down, but are always partly buoyed by a film 

 of air held on their ventral hydrofuge pubescence. 



