- Milkweeds are the sole source of food for Monarch butterflies. The Monarchs lay their eggs on milkweed plants and when they hatch the caterpillars feed on the the plants. The toxic sap in the milkweed makes the Monarch caterpillars and adults toxic as well, so predators avoid eating them.
- Milkweeds are an agricultural pest, competing with crops for water and nutrients. They can also be toxic to domestic animals such as sheep, horses and cattle.
- Control measures, in agricultural cropping systems, deplete the milkweed population which the Monarch butterfly relies on.
- Milkweeds make a beautiful addition to an ornamental garden and can provide an additional food source for the Monarch butterfly. Care should be taken to not let the milkweed plants that we grow in our gardens invade natural areas, unless they are native to your region. Swamp milkweed is native to PEI.