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!).

Apioceridae (Flower-loving Flies)
Apiocera indet. sp. 

Asilidae (Robber Flies)
Efferia benedicti 
Efferia indet. sp. 
Hodophylax basingeri 
Leptogaster eudicrana 
Leptogaster patula 
Megaphorus frustrus flavidus 
Megaphorus indet. sp. 
Stenopogon arnaudii
Bombyliidae (Bee Flies)

Anthrax daphne 
Apolysis indet. sp. 1 
Apolysis indet. sp. 2 
Apolysis indet. sp. 3 
Exepacmus johnsoni 
Exoprosopa caliptera 
Lepidanthrax eremicus 
Lordotus pulchrissimus 
Paravilla montivaga 
Paravilla syrtis 
Thyridanthrax melanopterus 
Toxophora virgata 
Triploechus novus 
Villa agrippina species complex

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