I grew up in the late 60s and the 70s. While we weren't farmers, we lived in a rural area, surrounded by farmland. Every spring, the tractors with their sprayers would hit the fields and blast the life out of anything that dared live where it wasn't wanted. Later in the growing season, the crop dusters would fly over and release clouds of yet more chemical concoctions. I don't know the names of the specific chemicals they used, Round-Up and 2-4D I remember, but for sure there were others too. Weeds and insects were the enemy of the factory farm, and all means necessary ensured their surrender. All, that is, except milkweed.
For some reason milkweed was, and remains, almost sacred. I've seen tractors go around patches of it, leaving it to grow unmolested by the toxins spread freely everywhere else. It is classified as a noxious weed (poisonous to livestock) and so should by law, be eradicated, but it is left to grow. I wonder why? Maybe this little guy? Nah... Maybe his mom?