Check out the milkweed on the right side of the drive. Do you know which organism eats milkweed? If you guessed a monarch caterpillar you are correct! The plant’s milky sap contains cardiac glycerides that when ingested causes rapid heart rate and general weakness, but this sap does not affect the caterpillars although it does cause them to become toxic to birds and other predators. There are other species that feed on the milkweed as well.