Phasia pusilla is a European species of fly in the family Tachinidae.
Its larval hosts include species in the families Lygaeidae, Cydnidae, and Anthocoridae.
British Isles, Belarus, Czech Republic, Hungary, Latvia, Moldova, Poland, Romania, Slovakia, Ukraine, Denmark, Finland, Norway, Sweden, Albania, Bulgaria, Corsica, Croatia, Greece, Italy, Portugal, Serbia, Slovenia, Spain, Turkey, Austria, Belgium, Channel Islands, France, Germany, Netherlands, Switzerland, Japan, Kazakhstan, Iran, Israel, Palestine, Mongolia, Canary Islands, Egypt, Morocco, Russia, Transcaucasia, Pakistan, Kyrgyzstan, China.