Be Careful Handling Milkweed

Milkweed is the only plant that monarch butterflies will use as a host plant for their larvae. It is vital that we plant milkweeds that are native to our area to help the dwindling population of monarchs in North America. However, it requires care in handling.

You can learn more about these native milkweeds and purchase seeds here:

Milkweed plants produce compounds known as cardenolides, also called cardiac glycosides. It is highly toxic substance found in milkweed sap which is toxic to animals. Its bitter taste warns away many of the animals and insects that try to eat milkweed leaves. Monarch larvae, however, are unaffected by the toxin, and they can sequester the cardenolides in their tissues. By feeding almost exclusively on milkweed leaves, the caterpillars accumulate enough of the cardenolides in their bodies to make them distasteful to predators. The toxic compounds stay with the caterpillars as they mature through subsequent stages of development, so they are toxic to predators both as larvae and as adult butterflies.

Milkweeds are named for their milky latex sap, which oozes from the stems and leaves when plants are injured. With the exception of butterfly milkweed (Asclepias tuberosa), all species ooze white sap when their tissues are damaged.

Humans are not exempt from this poison. Milkweed sap can be very dangerous if it gets in your eyes. This poison can cause corneal endothelial toxicity. This toxicity affects the innermost layer of the cornea and can cause symptoms such as blurred vision, light sensitivity and extreme pain. These symptoms often do not present immediately, which is why most patients and doctors never associate it with milkweed poisoning.

Milkweed corneal toxicity occurs when milkweed sap directly contacts the eye. Patients will notice redness and irritation of the eye(s) shortly after exposure. Within one to two days, the cornea begins to swell and cloud over, blurring the vision.

So, the next time you are working in the garden, remember these helpful Safety Precautions when handling milkweed:
• Wear gloves
• Avoid rubbing eyes or wiping sweat from brow
• Always wash hands  immediately after handling milkweed

Do not touch your face, nose, mouth and especially your forehead with milkweed sap on your hands. Even if your hands are dry the toxins from the sap remains on your skin until they are washed off. The sap can travel from your forehead into your eyes from the sweat on your forehead.

If you suspect that you may have milkweed poisoning, it is important that you seek medical help immediately.

You can find more information here: