Aquatic Macroinvertebrates - Coleoptera

 Key to Macroinvertebrate Life in Ponds and Rivers in Utah

Water Beetles

The Coleoptera Order

Family Adult picture
Description Habitat


trout stream beetles

Larvae are elongated, with flattened lateral projections, and 2 short spine like cerci (tails).

Adults have a broad appearance and are reddish brown to black. 

length 10-15mm
In cold mountain streams. Adults are often collected near the surface in eddies and on twigs and aquatic plants. 


long-toed water beetles

Larvae have clinging legs with large claws and clubbed antennae.

Adult bodies are hard and the head is nearly drawn into the thorax. They have a short, thick antennae.

length 5-10mm

Larvae are terrestrial.   Adults are typically found in stream riffles and along stream margins.

Only 1 genius Helichus have been collected in Utah.


predaceous diving beetles

Larvae are elongated and spindle shaped with oar-like hind legs and 2 cerci (tails).  Their heads are large with a large anterior prolongation (constriced neck).

Adults are ovoid shape  x-section and are shiny, brown, black, greenish, or yellow with and without spots.  Adults have long antennae.

length 10-40mm

Adults and larvae are found in slow moving streams, ponds, wetlands, and lake littoral zones.


riffle beetles

Larvae have stiff, cyclindrical bodies.  They have a single claw and a filamentous gill on their last abdominal segment.

Adults are small, hard-bodied and their heads are slightly withdrawn into their thorax.  Their legs are long and have 2 claws.

length 2-8mm
Found only In rapid moving fresh water.


whirligig beetles

Larvae have elongated slender body with long lateral respiratory filaments on abdomen, and 2 pair of hooks on last abdominal segment.

length 10-30 mm

Adults may appear to have 4 eyes (1 pair looking down and 1 pair looking up. Adult bodies are black, shiny and oval.

length 3-10 mm

In still and rapid moving fresh water margins


crawling water beetles

Larvae have an elongate, sclerotized body, two terminal filaments at the posterior end of abdomen, and some species have long dorsal projections of hairs or spines along their abdomen.

Adults have small heads, a plate that covers their hind legs, and skinny legs.  They are often yellow with black markings.  

length 2-8mm

In ponds and stream pools.  They are typically found in riparian debris and aquatic plants crawling along sticks and plant stems.


water scavenger beetles

Larvae have large toothed jaws that are readily visible from above.  They have four- segmented legs.

Adults have clubbed antennae and are often confused with dytiscidae.  They may have a metasternal spine or keel.

length 2-40mm

Found in a variety of aquatic habitats.

Back to My Organism has 3 pairs of legs