Vol. 86, No. 22, pp. 261-278 28 September 1973 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON DESCRIPTIONS OF THE LARVAE OF SOME PREDACIOUS WATER BEETLES ( COLEOPTERA : DYTISCIDAE ) By Paul J. Spangler and Robert D. Gordon Smithsonian Institution, Washington, D.C. 20560 and Systematic Entomology Laboratory, Agricultural Research Service, U.S. Department of Agriculture^ During our occasional local collecting trips in the past few years we have been searching for the immature stages of aquatic beetles belonging to genera whose larvae have not been described previously or whose larvae were described only briefly. As a result, we have obtained the larvae of Agabetes acuductus (Harris) and Matus bicarinatus (Say) and the larva and pupa of Laccornis difformis (LeConte). Descriptions of the immature stages of these species follow; bionomic notes are included. The illustrations for this paper were prepared by Mr. Michael Druckenbrod, Smithsonian Institution staff artist. Genus Agabetes Crotch Agabetes Crotch, 1873:401. Agabetes is a monotypic genus occurring primarily in shaded wood-land ponds although specimens occasionally have been collected in un-shaded ponds in or adjacent to wooded areas. The only species known in the genus, Agabetes acuductus, is recorded from southern Canada to Florida on the east coast and to Michigan, Missoiui, and Arkansas in the midwestern United States. Agabetes acuductus (Harris) C[olymbetes] acuductus Harris, 1829:164. Bionomics: Sherman (1913) discussed the habitat of A. acuductus and reported that the species is wingless. However, Leech ( 1942 ) dis-1 Mail address: % National Museum of Natural History, Washington, D.C. 20560. 22— Proc. Biol. Soc. Wash., Vol. 86, 1973 (261)
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