Immature beetles

THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

Aquatic Invertebrates in Pacific Northwest Freshwater Wetlands
An Identification Guide and Educational Resource

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Identify taxa

Jointed legsSix legs

Coleoptera

Immature beetles

	Gyrinidae (whirligig beetles) Body is long and soft with long filaments on each abdominal segment. The tip of the abdomen has four well-developed hooks. Each leg ends in two claws.

	Elmidae (riffle beetles) Body is long and hardened; may be cylindrical, slightly flattened, or hemispherical in cross section. The last abdominal segment has a plate on the underside that covers a small chamber which contains hooks and gills. The underside of at least the first 6 abdominal segments have a line or indentation on each side. Antennae are short.

	Dryopidae (long-toed water beetles) Similar to the Elmidae with a plate and chamber on the last segment, but the chamber doesn't have hooks or gills inside. Larvae are only semi-aquatic or are on shorelines.

	Haliplidae (crawling water beetles) The last segment of the abdomen is much narrower than the previous segment and does not have a plate or chamber underneath. The last abdominal segment tapers to a hook or long tail.

	Scirtidae (marsh beetles) Larvae have flattened, elongate bodies and very long antennae with many segments, somewhat resembling a roach.

	Noteridae (burrowing water beetles) The body is broad then tapers to a point. Legs are very thick and short. There are no gills, lobes, filaments, or hooks on the abdomen.

	Dytiscidae (predaceous diving beetles) Diverse group with slender legs, eight abdominal segments and prominent sickle-shaped mandibles. The last abdominal segment tapers to a point and may have two small tails. Some have filaments on the sides of the abdomen but lack hooks at the tip.

	Hydrophilidae (water scavenger beetles) Slightly flattened head with mandibles clearly visible. The body is mostly soft with a wrinkled appearance. The abdomen ends in very short lobes; abdominal filaments may be present but hooks are absent. Antennae attach to the head between the mandibles.

	Curculionidae (water weevils) The larvae are grub-like and do not have legs or prolegs.

	Sphaeriusidae ( Microsporidae) (minute bog beetles) Minuscule (<1mm) beetles with small lobes present on all abdominal segments. The 2nd segment of each antenna has a tiny filament that sticks out to the side.

	Coleopterans unlikely to be found in a wetland Helophoridae (helophorid beetles) Hydraenidae (minute moss beetles) Hydrochidae (hydrochid beetles) Psephenidae (water pennies)


	Resources

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