Tussock moth ID
I observed a mass of 50-100 caterpillars (not monarchs), about ⅓ inch long and white with black heads. The first stage of the larvae looks slightly furry and light brown. They are skeletonizing the milkweed, eating everything but the veins and ribs. Any idea what these might be?
These are milkweed tussock moth caterpillars. They are gregarious for the first week or so, and then will go their individual ways. They'll soon be furry with big tufts at each end of their body. The female lays an egg mass, and the larvae are synchronized in everything they do, including molting.