Yesterday I spent well over an hour checking a patch of milkweed for monarch butterfly eggs and caterpillars. I didn't find any eggs, but I found two caterpillars (very hopeful sign!), one about 2 days old, and this much bigger one. I went back today to see how it was doing only to discover it was no longer on the milkweed plant. I could see caterpillar frass on the leaves indicating it had been there. Looking around the immediate vicinity I was surprised to find it on a burdock leaf! I put it back on the milkweed, and went off looking for more caterpillars in the rest of the milkweed patch (found no more). When I got back about 45 min. later, this guy was back on the burdock.