Key to Aquatic Macroinvertebrates in Utah - Diptera

Key to Macroinvertebrate Life in Ponds and Rivers in Utah

Worm-like organisms with tentacles, brushes or tails typically belong to the order Diptera, or true flies. 

There are over 22 families of true flies found in Utah.  All organisms shown here are in the larva stage. 

Family Picture Description Habitat


Watersnipe Fly

Athericidae have several (typically 7) pairs of well-developed ventral pro-legs, dorsal and lateral filaments on each segment,  and a pair of divergent processes on the posterior end.

2-20 mm in length

Rapid moving freshwater, common in erosional areas in rivers and streams throughout North America


Net-winged midge

Blephariceridae have 7 distinct segments with a ventral sucker on each of the first 6 segments

4-12 mm in length

photo is a ventral view

Upper surface of rocks in fast moving water, occurs in mountainous regions throughout North America


Biting midge, (Buffalo gnat)

Ceratopogonidae are very slender.  Prothoracic and terminal prolegs may be present or absent, if present their bodies possess well developed bristles or spines

2-15 mm in length

Temporary ponds, tree holes, still and fast moving fresh water


Phantom midge

Chaoboridae have clear to transparent bodies.  The head is separated from their thorax.

8-15 mm in length

Large lakes to small ponds, throughout North America in still fresh water



Chironomidae have thoracic and terminal prolegs.  They are slender with slightly curved bodies and a well defined head capsule.

2-20 mm in length

Still and fast moving  water, wetlands, temporary and permanent wetted habitats throughout North America





Culicidae larvae have no prolegs and a large head.  They breath through a siphon located on the posterior end. 

5-15 mm in length

Still and slow moving fresh water throughout North America, often found near the surface.


Mountain Midge

Deuterophlebiidae larvae have flattened bodies, sucker-like lobes on 7 pairs of prolegs, and forked antennae longer than head.

3-10 mm in length

Fast moving fresh water  in mountainous streams throughout western North America


Dixid midge

Dixidae are elongate and slender with 3 thoracic segments.  The abdomen terminates in a breathing tube and lateral paddle-like structures

3-7 mm in length

Fast and still fresh water, throughout North America in a variety of aquatic habitats


Aquatic long-legged fly

Dolichopodidae abdomens terminate in a concave pit surrounded by short projecting lobes.  Abdomen with or without prolegs

3-10 mm in length

Mostly still water, occur throughout North America


Dance Fly

Empididae may have 7-8 prolegs.  The anterior end of the abdomen ends in a cone shaped point. 

2-7 mm in length

Fast moving water, occur in variety of aquatic habitats throughout North America


Shore Fly (Brine fly)

Ephydridae have wrinkled and extendable body, with or without prolegs

2-12 mm in length

still or slow moving water.  Ephydridae can withstand hard conditions, including high salinity, temperatures and pollution



Muscidae have welt like prolegs and have 2 short breathing tubes

6-14 mm in length

Fast moving and still water, occur in various aquatic habitats throughout North America


Moth Fly

Psychodidae lack prolegs, abdominal segments are subdivided, a short hardened breathing tube at the terminal end of abdomen

<5 mm in length

Fast moving and still fresh water, occur in clean to highly polluted waters throughout North America


Phantom cranefly

Ptychoperidae have extendable bodies and long extendable breathing tube. Prolegs are present on first 3 abdominal segments

15-60 mm in length

Still fresh water, occur in ponds and wetlands throughout North America


Marsh Fly

Sciomyzidae have elongated, cylindrical body with a pointed anterior end.  Posterior end is surrounded by several short lobes and may have a breathing tube.

5-15 mm in length

Still water, occur in wetlands, marsh habitats throughout North America (not common)


Black Fly

larvae are cylindrical with a bulbous distal abdomen,  distinct fan-like brushes occur on the sides of their head

3-12 mm in length

Flowing water, occur in running water habitats throughout North America


Soldier Fly

Stratiomyidae has a leathery feel and appearance due to calcium deposits.  Head extends from thorax.

No prolegs

5-30 mm in length

Fast moving and some still fresh water, occurs throughout North America along aquatic habitat margins


Rattail maggot (Flower Fly)

Syrphidae larvae are soft-bodied, semi-transparent, and wrinkled. They breath through a long breathing tube on the posterior end. Some species have ventral prolegs.

5-25 mm in length

Still waters, tree holes, bogs, occur throughout North America


Deer Fly (Horse Fly)

larvae are elongate, cylindrical and tapers to a pointed cone at both ends, there are no breathing tubes at the posterior end of their abdomen

10-50 mm in length

Fast moving and still fresh water, common throughout North America


Primitive Crane Fly

larvae are slender and elongate, six long spine-like filaments that extend from the posterior end of their abdomen

10-20 mm in length

Fast moving fresh water, occurs throughout North America


Crane Fly

larvae have elongated cylindrical shape, head capsule is retracted into their thorax,  abdomen terminates in 2 spiracles that are surrounded by short fleshy lobes

10-100 mm in length

Fast moving and still fresh water, occur in depositional habitats throughout North America

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