Leave them be.
They collect various insects from plants and trees.
They won't sting you if you don't bother them.

I was more worried about the tree than me, it doesn't look as healthy as the others. More needles fall off,less pine cones, some limbs have like a black dust on them. And then there's the question of why just that one, there's not a single wasp or yellow jacket on any of the others and they are all together. But I'll take your advice, even though I have to run by it when I'm mowing.

For the sound of your second post, the tree has pesky insects living on it -- possibly conifer aphids or other sap-sucking pests.

Might consider having a certified arborist of two out for an on-site evaluation.

Or if you do locate the insects, you might try periodic harsh water sprays to blast them off. The effectiveness of that depends upon just how bu=ig and heavily needled the trees are.