Are flies pollinators?

My euphorbia was abuzz today with flying bugs. There are no less than 4 winged creatures in the picture.

But only two of them look like a bee to me -- this furry faced guy here.

And this striped-back one here.

 

The rest looked like common flies or flies with blue bottoms (when the light was right.) And the flies way outnumbered the bees.

 

 

See how in the last picture, the creature that looked like a fuzzy fly revealed itself to be blue bottomed?

I looked around the web and found that flies can be pollinators at sites such as this one by the U.S. Forest Service. Apparently flies like pale, putrid, funnel-like flowers -- which would explain their attraction to my euphorbia (which doesn't really smell that bad....) And true bees have 2 sets of wings (four wings total) -- so I am thinking that at least one of my 'bees' way above is actually a bee-mimic.

And all of this and I am not sure it is going to matter for my fruits or veggies. Flies are pollinators -- but they won't likely be attracted to the bright, sweet flowers of my fruit starts, bushes, and trees. And my veggies aren't going to need pollination to deliver tasty goodness.

More importantly, I am going to have to figure out what to do to encourage my well-protected veggies to grow....