Skeletonizers

Yep. Look what Rayetta's butterflies are up to. More and more I am sure, maybe, these particular vermin are baby border patch (Chlosyne lacinia) caterpillars. Not only are they eating up the Helianthus annua, now they are starting in on the Verbesina virginica. This bunch, not long ago were eggs. They probably have not molted yet, even once. Look at them go. When they are little like this, they operate as a herd. That's why they are bunched up. Later on, they spread out some.

This bunch shall completely skeletonize that great big leaf in a tousand or maybe two tousand shakes of a lamb's tail. Mercy!