Billaea triangulifera is a species of fly in the family Tachinidae. It is a parasitoid of larval Prionus coriarius beetles, piercing the beetle near its spiracles.
Belarus, Czech Republic, Estonia, Hungary, Poland, Romania, Slovakia, Ukraine, Denmark, Finland, Norway, Sweden, Bulgaria, Italy, Serbia, Austria, Belgium, France, Germany, Switzerland, Japan, Russia, Transcaucasia, China