Monarchs and Milkweed

The monarch and milkweed. These beautiful butterflies cannot exist without this specific plant, but unfortunately for monarchs, milkweed is in short supply. Milkweed is a plant that typically has rosy pink flowers, although it does come in many varieties. These varieties can thrive in humid conditions, in the full sun, and even in dry climates. And the plant is a perennial, so each year it will come back even after the harshest of winters.

Milkweed is monarch caterpillar food. In fact, it is the only food that monarch caterpillars eat. But the availability of milkweed is rapidly decreasing. Simultaneously, the monarch population is decreasing as well. 

Why are monarch butterflies dying

Monarch butterflies are facing extinction. But why are monarch butterflies dying? The short answer is from a lack of food. But they are under attack from pesticides, land development, and climate change. Two of these three result in a lack of milkweed.

Pesticides and land development are ravaging monarch’s only food source. 

• Herbcides.Glyphosate is the most used herbicide in agriculture to control weeds. But it isn’t only used in agriculture, it is also used in roadside ditch maintenance, in public parks and on residential lawns. The rampant use of glyphosate across the landscape has contributed to milkweed decline.
• Land development. Between the monarchs’ winter habitat and summer breeding grounds, they have lost substantial milkweed habitat due to land development. Much of the natural landscape that was once filled with milkweed – and other wild plants – has now become developed property. With the locations they have left to gather getting fewer and far between, the population of milkweed and monarchs are rapidly decreasing. 

Because of monarchs’ steady decline, it is now a candidate to be listed as endangered under the Endangered Species Act. But with pesticide use at an all-time high, something needs to be done to help these butterflies that are struggling to survive. 

Milkweed decline

It is easy to put two and two together. The disappearance of milkweed in North America has led to the decrease in monarch butterfly populations. 

In the late 1990s, farmers began planting genetically engineered crops that could withstand the application of glyphosate, aka Bayer-Monsanto’s Roundup herbicide. Large-scale farms at that point became able to utilize  an herbicide that destroys milkweed and other plants while allowing crops to survive. This ultimately led to the decimation of milkweed across large swaths of land across the United States.

The United States Geological Survey competed a study in 2017 that stated over 860 million milkweed stems in the northern United States were lost in the decade prior. 

The loss of milkweed means that monarch caterpillars no longer have a reliable food source — the only food source that they depend on. In order to help Eastern monarch butterfly populations rebound, it would require nearly 2 billion new milkweed plants. 

Insecticides on Milkweed Also Threaten Monarchs

As the monarch caterpillar emerges from its eggs on the milkweed leaf, it will soon rely on the same plant for sustenance. But if the plant or land surrounding it has been sprayed with certain harmful insecticides  the baby monarch could begin poisoning itself unknowingly.

If milkweed is sprayed with harmful insecticides that are ingested by the monarch caterpillar, it could soon be expelling green vomit. If it does not die from the poison but cannot find milkweed that isn’t toxic, it has no chance of survival. Even if the caterpillar ingests small amounts of the insecticides, it can be at risk of death when it forms its chrysalis. 

One study found 64 different insecticide residues in milkweed in California. Every milkweed sample was contaminated, and 32% contained insecticide levels known to be lethal to monarchs.

Unfortunately, certain insecticides like neonicotinoids are ‘systemic’ and do not wash off plants. They can continue to poison insects that use it for sustenance for days, weeks, or months. Systemic pesticides are chemicals that are absorbed by a plant. The chemicals are then distributed throughout the plant tissue, going to the roots, leaves, stem, flowers, and/or fruit. Because systemic pesticides are water-soluble, they travel through the plant when it absorbs water to transport to its tissues. 

Growing milkweed

Sadly, there are stores that sell milkweed that is contaminated with insecticides – even though the majority of the consumers who buy milkweed have the intention to provide a safe haven for monarch caterpillars and butterflies. 

To prevent more monarch suffering, consider using the following tips to avoid having toxic milkweed in your garden:

• Before you buy milkweed, ask your garden store if it was treated with neonicotinoids or other systemic insecticides.
• Find an online source that grows milkweed without insecticides.
• Do not confuse “safe for beneficial insect” labels as safe for monarchs. They do not refer to caterpillars.
• Make a neighborhood commitment to stop spraying neonicotinoids and other harmful pesticides on your lawns and gardens and to switch to organic products that carry the OMRI (Organic Materials Review Institute) label. Even if you do not spray them yourself, your milkweed is at risk if the wind carries it from your neighbor’s lawn, or if the rain washes it into your lawn.

If you’re looking for other ways to get involved to help save monarchs, join Friends of the Earth’s email list and get involved by signing petitions to help make change. Join thousands of other concerned activists around the country and petition our government to make policy changes that get toxic chemicals out of agriculture. Sign and stand with your fellow activists and demand home and garden retailers stop selling pollinator-toxic pesticides. And use your voice to get toxic pesticides out of our food system. We cannot save the monarchs alone. We need help from concerned people like you!