We used to have lots of black and yellow striped bumblebees here in So Cal when I was a kid, then they slowly disappeared. These parasitic flies used to attack the bumblebees, but now that the bumblebees are gone they adapted and now are going after the honeybees. Very sad. Not as much left as pollinator flies and butterflies around now either.
Maybe something else will adapt and take the bees place to pollinate...