Milkweed (food plant) + tussock ("thick tuft or clump") + moth (gregarious caterpillars) =
Milkweed Tussock Moth Caterpillar. How...obvious. I like it when something is called exactly what it is. (Okay, so I did have an edge in that I already knew there were such things as tussock moth caterpillars.)
Another serendipitous discovery (and a new species for me!) while I was out looking for the frogs and Snap, who abandoned the Mud Puddle on or after the full day of rain we had. (I'm hoping they come back when things dry out again.)
The hasn't-let-me-down-yet-though-it-may-take-some-searching-it's-so-big caterpillar book I use (Caterpillars of Eastern North America) notes that the milkweed tussock moth caterpillars seem to prefer older milkweed and therefore don't appear to compete directly with Monarch caterpillars.
