Dancing Butterflies

I've noticed the last couple of days that we have a cloud of little yellow butterflies on a small sand plain where the dumpster used to be.

You can barely see them in the picture below.



I believe they're sulphur butterflies. We have these little clusters of them in several other spots in the yard.



I read that they're sometimes called 'mud puddle butterflies' because they cluster at small mud puddles to sip from them. They're supposed to be getting minerals that way. The ones in this picture all look similar but we have several different kinds of these butterflies, some larger and some more orange than these.



I love how they cluster, and then rise and dance in the air when we pass by. What's also interesting to me is that we have other damp areas of ground in the yard where they don't cluster. I think that if I just knew more about it, I could conclude something about the composition of soil in those areas.

At our previous house, which backed to a pond, I always wondered why we didn't see more butterflies, since there were abundant mud flats there. I suspect it was because all the houses that backed to the pond had lawns, and many of them used herbicides/pesticides.

It always amazes me how little I really know about the world around me.