Unlike most other insects with “fly” in their name, nearly all Dipterans possess a single pair of wings. This distinguishing character is where the name Diptera comes from, translated as “two-wings” in Greek.  For those Dipterans than have “fly” in their common name, you will notice that it is written as two words, for example crane fly or fruit fly.  In contrast, other insects with “fly” in their common name are usually written as one word, such butterfly and dragonfly.  Diptera currently includes more than 150,000 species in an estimated 160 families worldwide.  Some examples of the most diverse groups include the Muscoidea, consisting of house flies and dung flies, as well as the Asiloidea, which includes the Bee Flies and Robber Flies.  Also, while there are at least six insect Orders with gall-forming insects, Diptera has the greatest number of species, most of which are in the family Cecidomyiidae (gall midges).

The taxa listed below have been added to the list based on museum collections or verifiable observations.  Most specimens are housed in the GMDRC museum collection or at the UC Riverside Entomology Museum.  Taxa that have only been observed (marked with *) are only added to the list if there is a certain level of confidence on the ID and it represents a taxon that had not previously been recorded here.  A taxon labeled with “indet. sp.” indicates it was indeterminable beyond a certain rank.  Each scientific name is linked to a profile page on the Iowa State University BugGuide. To learn more about the species, click on the double arrow (⇒) to the right of the scientific name; this will take you to the iNaturalist taxon page, which may show locations of observations, photos, and other natural history details. This list can be downloaded as a pdf (coming soon!).

Cecidomyiidae (Gall and Forest Midges)
* Asphondylia auripila

Muscidae (House Flies and Allies)

* Musca domestica

Mydidae (Mydas Flies)

Pseudonomoneura californica
Rhaphiomidas acton
Rhaphiomidas tarsalis

Stratiomyidae (Soldier flies)

Dieuryneura stigma

Syrphidae (Hover Flies)

Eristalis indet. sp.
* Copestylum apiciferum
* Copestylum avidum
* Copestylum haagii
* Copestylum mexicanum
* Eupeodes volucris
Polybiomyia sayi
* Pseudoscaeva diversifasciata

Tachinidae (Parasitic Flies)

Oestrophasia indet. sp.
Ormia indet. sp.

Tephritidae (Fruit Flies)

* Trupanea nigricornis
* Euarestoides acutangulus