Ospriocerus aeacidinus
(Williston, 1886)
robber fly
Ospriocerus aeacidinus is a large robber fly ( Asilidae) native to western North America. The was historically recorded as far east as Nebraska, Kansas, Oklahoma, and Texas, but has been documented in recent years in relictual hilltop prairie in northwestern Missouri and southwestern Illinois—representing significant eastern range extensions. are active with -mimetic coloration. The species is considered a grassland associated with dry prairie remnants, particularly those linked to the Loess Hills landform.
Pronunciation
How to pronounce Ospriocerus aeacidinus: /ˌɒspriˈoʊsərəs eɪəˈsɪdɪnəs/
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Identification
Distinguished from the related western Wyliea mydas by its black body and wings with red coloration on the (W. mydas has wholly black abdomen and red wings). Resembles mydas flies superficially but has short typical of Asilidae rather than the elongate clubbed antennae of Mydidae. The -mimetic coloration—presumably modeled after spider wasps (Pompilidae: Pepsis, Hemipepsis)—features black body and wings with contrasting red abdominal markings.
Habitat
Dry hilltop prairie remnants, particularly those associated with the Loess Hills landform. Inhabits critically imperiled sand and loess prairie characterized by sparse vegetation, exposed substrates, and xeric conditions.
Distribution
Western North America extending into Mexico; historically recorded from Nebraska, Kansas, Oklahoma, and Texas eastward. Significant eastern range extensions documented in northwestern Missouri (Loess Hills) and southwestern Illinois (hill prairies), representing hypsithermal relict in isolated prairie remnants.
Behavior
are active aerial . Extremely wary; individuals rarely allow approach within 12 feet and exhibit repeated long, loping escape when disturbed.
Ecological Role
Apex in grassland . As a large robber fly, likely regulates of other flying insects. Its occurrence in relictual prairie contributes to the biodiversity value of these critically imperiled .
Human Relevance
Documented as a new state record for Missouri in 2009, highlighting the importance of continued entomological survey of imperiled . Serves as an for high-quality prairie remnants.
Similar Taxa
- Wyliea mydasSimilar -mimetic coloration and western distribution, but distinguished by red wings with black versus black wings with red abdominal markings
- Mydas flies (Mydidae)Superficially similar body form and coloration, but distinguished by short (robber flies) versus elongate clubbed antennae (mydas flies)
- Spider wasps (Pompilidae: Pepsis, Hemipepsis)Presumed mimicry model; distinguished by Hymenoptera characteristics including constricted waist and different wing venation