Description: 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.

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

Description: 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.

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

Description: 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.

Habitat: Temporary ponds, tree holes, still and fast moving fresh water.

Other Images: 

Description: Chaoboridae have clear to transparent bodies. The head is separated from their thorax. 8-15 mm in length.

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

Description: Chironomidae have thoracic and terminal prolegs. They are slender with slightly curved bodies and a well defined head capsule. 2-20 mm in length.

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

Description: Culicidae larvae have no prolegs and a large head.  They breath through a siphon located on the posterior end. 5-15 mm in length.

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

Other Images: Lavae       Pupae 

Description: Deuterophlebiidae larvae have flattened bodies, sucker-like lobes on 7 pairs of prolegs, and forked antennae longer than head. 3-10 mm in length.

Habitat: Fast moving fresh water  in mountainous streams throughout western North America.

Description: 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.

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

Description: Dolichopodidae abdomens terminate in a concave pit surrounded by short projecting lobes. Abdomen with or without prolegs. 3-10 mm in length.

Habitat: Mostly still water, occur throughout North America.

Description: Empididae may have 7-8 prolegs. The anterior end of the abdomen ends in a cone shaped point. 2-7 mm in length.

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

Description: Ephydridae have wrinkled and extendable body, with or without prolegs. 2-12 mm in length.

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

Description: Muscidae have welt like prolegs and have 2 short breathing tubes. 6-14 mm in length.

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

Description: Psychodidae lack prolegs, abdominal segments are subdivided, a short hardened breathing tube at the terminal end of abdomen. Less than 5 mm in length.

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

Description: Ptychoperidae have extendable bodies and long extendable breathing tube. Prolegs are present on first 3 abdominal segments. 15-60 mm in length.

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

Description: 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.

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

Description: Larvae are cylindrical with a bulbous distal abdomen, distinct fan-like brushes occur on the sides of their head. 3-12 mm in length.

Habitat: Flowing water, occur in running water habitats throughout North America.

Description: Stratiomyidae has a leathery feel and appearance due to calcium deposits. Head extends from thorax. No prolegs. 5-30 mm in length.

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

Description: 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.

Habitat: Still waters, tree holes, bogs, occur throughout North America.

Description: 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.

Habitat: Fast moving and still fresh water, common throughout North America.

Description: Larvae are slender and elongate, six long spine-like filaments that extend from the posterior end of their abdomen. 10-20 mm in length.

Habitat: Fast moving fresh water, occurs throughout North America.

Description: 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.

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