Did you have any ideas about these mini green barrels that I saw on a leaf?
They are what entomologists call frass, or what kids call poop. Same thing.
This green frass was on Dutchman’s Pipevine, which is the host plant of the Pipevine Swallowtail, so that’s whose frass it is. All caterpillars leave frass behind, though some roll it up in a leaf to hide it, or shoot it out their butt with explosive propulsion so as to not alert predators to their presence. Pipevine Swallowtail caterpillars do nothing with their frass–they just leave it there where it falls. As you can see it really is kind-of attractive, different shades of green and uniquely shaped. It could be art!
You never know when this information may come in handy! Just wait…