Diptera (true flies)

Order Diptera Description

The order Diptera contains the semi-aquatic and aquatic true flies.  True flies are named with the word "fly" as separate from the remainder of the name.  For example, black fly is a true fly while mayfly is not.  The majority of species in Diptera are terrestrial, but there is still a greater number of aquatic species in Diptera than in any other order.  In order to be considered an aquatic insect, the species must have aquatic pupal and larval growth stages.  Diptera have been documented in every aquatic habitat so their distribution is quite variable. 


Diptera Families:
Click on each below to display information.


AthericidaeFamily Athericidae

Aquatic Snipe Flies

Athericid larvae are predators that feed on other aquatic insects, particularly Ephemeroptera (mayfly) larvae. These larvae are most common under stones or rocks in riffles of streams and rivers. The larvae are medium in size compared to other Diptera larvae. The average body length is 10-18mm.  Athericid larvae have a long, worm-like body and a pair of prolegs on each abdominal segment.  There is only one proleg on the final abdominal segment, abdominal segment number 8.  There are two fringed tails at the end of the abdomen.  Athericid females have a unique egg- laying behavior.  Females will lay their eggs on branches that overhanging water.  After a female lays her eggs she stays with them until she dies.  Other females are attracted to the same spot as well so that a pile of dead flies soon accumulates.  When the larvae hatch they must crawl out of this pile of dead female flies before they can drop from the branch into the water.



Diptera Life History
Larvae and Pupae
The larvae of many species are free-swimming while others burrow in the substrate.  Most Diptera larva are worm-like in appearance, and possess a head capsule.  The larvae may be distinguished from most aquatic insects by the lack of jointed thoracic legs.  Other than this unifying feature, the morphology of Dipteran larvae is very diverse.   

The adults of most Diptera species are found near the larval habitat.  One exception is found in adults that require a blood meal.  These insects may regularly travel away from the water source. The adults have wings and antennae. 

Feeding Habits
Larval feeding habits may be collector/gatherer, shredding, filtering, or predaceous depending on the species.  The majority of Dipteran larvae are herbivorous.  

Ecological Importance
Diptera are very abundant in aquatic ecosystems and thus they are a reliable food source for many vertebrates.  Some families, including Simuliidae (black flies) and Culicidae (mosquitoes) are of economic importance due to their role as human pests and vectors for diseases.


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