I found it on my back patio. Dee-lightful. I got the pics just before asking the kids to hose off all the brick. The culprits have been hanging out far too often back there and it was getting....eeww.
I'm sure you understand.
These butterflies do, however, enjoy partaking of the mineral content of the ... offerings. [We also see butterflies on carrion, which is disgusting, but there's no accounting for tastes.] These offerings were somewhat wetter than the above, but left by the same creature.
So, let me know in the comments what is responsible for this