Phasia obesa is a species of 'parasitic flies' belonging to the family Tachinidae subfamily Phasiinae.[1] [2] [3] [4] [5]
This fly is present across the palaearctic ecozone, British Isles, Czech Republic, Estonia, Hungary, Lithuania, Poland, Romania, Slovakia, Ukraine, Denmark, Finland, Norway, Sweden, Bosnia and Herzegovina, Bulgaria, Corsica, Croatia, Cyprus, Greece, Italy, Portugal, Serbia, Slovenia, Spain, Turkey, Austria, Belgium, France, Germany, Liechtenstein, Netherlands, Switzerland, Japan, Kazakhstan, Iran, Israel, Lebanon, Palestine, Mongolia, Morocco, Russia, China, Transcaucasia.[5]
The adults grow up to 4- long. Their large compound eyes are reddish. Antenna, including arista, are black. The body is greyish, with four longitudinal black bands interspersed with clear bands of the same thickness on mesonotum. The side of thorax shows black setae. The abdomen is black. The large wings show a light brownish shading. The cell R5 is closed at the edge. Basicostae are black. In the males eyes are separated by a distance narrower than the ocellar triangle.
Adults can mostly be encountered from June through September feeding on nectar of flowers (especially of Asteraceae species).
Larvae of Phasia obesa are parasitoids on adults or nymphs of various species of plant bugs (Neottiglossa sp. and Zicrona caerulea Pentatomidae, Leptopterna dolabrata and Beosus maritimus Miridae, Lygus pratensis, Lygus rugulipennis Lygaeidae, Myrmus miriformis Rhopalidae, etc.).