and lakes, and are usually found creeping or crawling over submerged vegetation. They are not good swimmers.

TROUT-STREAM BEETLES Family Amphizoidae Not illus.

Identification: Elongate-oval, rather convex dorsally, somewhat flattened ventrafly. Dull brownish to dull black. 11-16 mm. Aquatic, occurring in streams in far West.

Adults and larvae live in the icy waters of swift mountain streams. They cling to driftwood, debris, or to stones in eddies where the water level remains fairly constant. One species lives in relatively warm quiet water in streams near Seattle. Adults

swim very feebly or not at all. Adults and larvae are apparently predaceous.


Identification: Shape often distinctive: elongate-oval, convex, streamlined; hind legs flattened and fringed with hairs. Hind tarsi with 1 or 2 claws. Front tibiae lacking spines. Antennae threadlike. Scutellum usually visible. Black, brown, or yellowish, often with light markings. 1.4-35.0 mm.

Members of this fairly large group are abundant in ponds, lakes, and streams. They are excellent swimmers, and when swimming move the hind legs in unison; water scavenger beetles (Hydrophilidae, p. 156), with which dytiscids may be confused, move the hind legs alternately when swimming. Predaceous diving beetles frequently fly to lights. Adults and larvae are highly predaceous, and feed on various small aquatic animals, including fish. Larvae (called water tigers) have large sicklelike jaws, and suck the body contents of the prey through channels in the jaws; they do not hesitate to attack an animal larger than themselves.

BURROWING WATER BEETLES Family Noteridae Identification: Similar to Dytiscidae but scutellum hidden and front tibiae often with a curved spine. Hind tarsi with 2 claws. Black to reddish brown. 1.2-5.5 mm.

This is a small group whose members are similar in appearance and habits to dytiscids. They are most common in the southeastern states but a few occur in the Northeast. Larvae burrow into the mud near the roots of aquatic plants (hence common name of the group).

Superfamily Gyrinoidea

This group contains a single very distinctive family that differs from nearly all other beetles in having 2 pairs of eyes, and from other Adephaga in having short clubbed antennae.

WHIRLIGIG BEETLES Family Gyrinidae Identification: Elongate-oval, flattened, 3-15 mm. 2 pairs of compound eyes, 1 dorsal and 1 ventral. Black, rarely dark metallic green. Front legs long, slender, middle and hind legs very short, flattened, not fringed with hairs. Antennae short and clubbed.

These beetles are often seen swimming in groups in an odd gyrating fashion on the surface of ponds and streams. Their 2 pairs of eyes enable them to watch for enemies and prey both above and below the water surface. They swim rapidly and are as much at home below water as on the surface. Adults and larvae are predaceous. Some adults when handled give off an odor similar to that of pineapples.

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