I've got a few Tropical Milkweed covered in this moth's caterpillars? I realize they are native but does anybody do anything about it? Or should I just let them be?
You could put the caterpillars on some native milkweed and pull up the tropical.
I'm more concerned with the notion they might destroy my milkweed right when the Monarchs need it most. I had roughly 10 adult Monarchs in my garden today many of which were laying eggs.
10 Monarchs all at once? That's incredible. I'd watch to see how many Tussock cats you have. I generally leave everything to nature, except to bring Monarch cats in to raise. But, those Tussock moths can be destructive. It depends on the numbers of eggs that get laid.
I didn't see my first Monarch till about a month ago. Then last week I noticed a large number of very big cats in one of my milkweed patches. Now I have adults coming out of my ears.
As far as the Tussock Moths are concerned I'd say I have about 30 cats all on one plant. They seem to stay together on the same leaf till it's gone then move en mass to the next leaf.