These known carcinogens are among 25 cancer-linked chemicals the FDA allows in our food system. It was a Monarch Butterfly. I had to share the wonderful news about seeing the Monarch Butterfly with my husband. The Monarch Butterfly or simply monarch is a milkweed butterfly in the Nymphalidae family. Monarch butterfly populations are dropping fast – falling over 80% in the east and 95% in the west since the 1990’s.