Why Is Milkweed Illegal? Controversy explained!!

Every autumn, thousands of monarch butterflies migrate long distances to overwinter in forested groves along the California coast. But over the past few decades, western monarch populations have plummeted by over 99% from millions to just thousands of remaining butterflies. This alarming decline has led to a flurry of conservation efforts aimed at protecting these iconic orange and black insects.

Central to the survival of monarchs is their reliance on milkweed. Female monarchs only lay their eggs on milkweed plants, and caterpillars exclusively eat milkweed leaves. With milkweed habitat shrinking across the U.S., restoring milkweed stands has become a major priority. However, some species of milkweed have been labeled noxious weeds and even banned for sale in certain areas, sparking debate among conservationists.

So why has milkweed become illegal in parts of California and other states working to save vanishing monarchs?

The short answer: Some counties prohibit the popular non-native tropical milkweed in nurseries over concerns it fosters pathogens deadly to monarch butterflies. But many experts argue all milkweed species host parasites and that bans further threaten monarchs by reducing plant havens for breeding and feeding. The debate centers around whether climate-driven shifts in monarch winter breeding make tropical milkweed harmful or an essential habitat resource.

In this in-depth post, we’ll cover the historical opposition to milkweed, new bans on tropical milkweed intended to protect western monarch populations, arguments from researchers who say the prohibitions are misguided or even counterproductive, and recommendations for supporting monarchs moving forward.

Monarch Butterflies Rely on Milkweed Plants to Survive

Monarch butterflies and milkweed plants have evolved in interdependent lockstep for millennia. As the only food source caterpillars can eat, milkweed is sole nursery of baby monarchs.

Adult monarchs sip nectar from diverse blooms, but exclusively lay eggs on milkweed leaves to continue their life cycle. Once eggs hatch, the hungry monarch caterpillars feed on milkweed, which contains protective chemical compounds incorporated into the developing butterflies to defend them from predators.

There are over 73 native milkweed species across North America that monarchs utilize for breeding, feeding, and shelter. But the fate of both insects and plants has become increasingly precarious over the past 20 years.

Western Monarch Butterfly Populations Have Plummeted

Western monarch butterflies that overwinter along California’s coast once numbered in the millions. But since the 1980’s, western monarch counts have declined a staggering 99.9% to fewer than 1,914 butterflies observed overwintering in 2020.

While the western monarch count rebounded slightly to around 250,000 last year, researchers warn the overall trend still points to vanishing populations. A 2019 species assessment by the U.S. Fish and Wildlife Service states that western monarchs face a high risk of extinction without urgent conservation action.

The reasons for vanishing western monarchs are multifaceted but largely tied to habitat loss from rapid development and widespread herbicide use. Milkweeds and other native wildflowers the butterflies rely on have been erased across farms, roadsides, parks and backyards.

Addressing these habitat pressures has become a top recovery strategy to stabilize imperiled western monarch numbers.

Historical Bans on Milkweed Due to Livestock Impacts

Long before the current monarch conservation crisis, milkweed has been controversial and deemed a nuisance weed in some areas.

Common milkweed (Asclepias syriaca) grows readily from vigorous underground root systems and spreading seeds. This resilience allows it to flourish in gardens, fields, and uncultivated land. But what makes it essential for monarch reproduction can also make common milkweed challenging for farmers and gardeners seeking tidy, controlled plots of land.

Importantly, common milkweed contains cardiac glycosides that are toxic to livestock like cattle, horses, and sheep in large doses. If milkweed infiltrates crop fields or cattle pastures, there is risk of sickened animals.

For this reason, many agricultural communities, especially across the Midwest, have historically banned or discouraged the propagation of common milkweed. These traditional restrictions have continued even as views on native plants and support for endangered wildlife like monarchs has markedly shifted.

So remnants of old rules designating milkweeds as toxic pests that threaten livestock health still designate them as “noxious weeds” in some city and county laws. This has created conflicting messages for residents about whether removing or planting common milkweed supports conservation.

Non-Native Tropical Milkweed Widely Used to Support Monarchs

In backyard habitat projects aimed at nurturing more monarchs, a popular non-native plant called tropical milkweed (Asclepias curassavica) has been widely cultivated.

Tropical milkweed grows fast in pots and garden beds across much of the U.S. With vivid orange and yellow blooms, this tropical species flowers through fall and winter when many native milkweeds go dormant. This extended flowering period and year-round availability provides breeding and feeding habitat when monarchs need it most.

Unfortunately, sections of California and a few other states have recently banned the sale of tropical milkweed over mounting concerns it may actually threaten monarchs despite good intentions behind planting it.

Counties Begin Banning Tropical Milkweed to Protect Monarchs

In June 01, 2022, the California Department of Food and Agriculture categorized tropical milkweed as a “noxious weed”. This designation from the state department allows individual counties to prohibit propagtion and nursery sales of tropical milkweed if they determine it jeopardizes local ecosystems or agriculture.

Spurred by worries over climate-related shifts in monarch behavior that may increase disease transmission, several California counties have enacted tropical milkweed sales bans. Marin, Ventura, Contra Costa and San Mateo counties now prohibit retail nurseries from selling potted tropical milkweed.

County agricultural commissioners point to research warning winter-breeding monarchs clustered on tropical milkweed allows deadly parasites to accumulate on plants and infect vulnerable caterpillars. Native milkweeds die back seasonally, which may limit overwintering parasite loads.

The nonprofit Xerces Society, which coordinates western monarch overwintering counts, strongly supports restrictions on tropical milkweed sales and propagation to protect monarchs from outbreaks seeded by the non-native plant.

They along with county officials argue residents should instead be encouraged to grow native milkweeds beneficial for local butterfly populations without disrupting migration instincts honed over millennia.

Monarch Researchers Dispute Whether Bans Will Help

However, not all Lepidoptera scientists agree that taking tropical milkweed out of nurseries will aid declining western monarch butterflies.

Dr. Art Shapiro, an ecology professor at UC Davis with over 60 years studying monarch populations, calls the ban rationale “hogwash”. He and other experts argue all milkweed contains some level of parasites, and that loss of breeding habitat poses greater dangers to imperiled monarchs.

Shapiro believes winter breeding in California is not caused by tropical milkweed but is instead climate driven impacting many species. He states that removing tropical milkweed eliminates important habitat, asserting “Planting milkweed of any kind in your garden — tropical or native — there’s unlikely to be enough of it to do any good, but it’s not going to do any harm.”

Dr. Hugh Dingle, emeritus professor of entomology at UC Davis, suggests that rather than tropical milkweed, warming temperatures over decades fail to provide monarchs consistent seasonal signals for migration and reproduction.

Dingle thinks banning tropical milkweed distracts focus from bigger issues like pesticides and ecosystem mismanagement. He contends safe winter breeding sites on tropical milkweed may become essential as climate change alters overwintering behaviors.

Dr. David James, a Washington State University professor studying western monarchs, states “The Monarch is adapting to our warming climate and in doing so a proportion of the population is now spending winters breeding in urban near-coastal California using tropical milkweed as the host plant.”

James cautions against removing vital habitat resources that monarchs rely on for adjusting to human-caused disruptions.

Mixed Government Messaging Causes Milkweed Confusion

Beyond clashing scientific perspectives on tropical milkweed impacts, conflicting public policies have added confusion. Across the U.S., federal, state, county, and city laws offer contradictory directives on whether common citizens should be ripping out or actively planting milkweed to conserve fragile pollinator species.

For example, while Overland Park and Lawrence, Kansas prohibit common milkweed, the state of Kansas Department of Agriculture confirms “all Kansas milkweeds are native and beneficial”. They do not consider common milkweed a noxious plant.

Yet Kansas city rules based on outdated views of milkweed toxicity penalize residents trying to support wildlife. This leaves gardeners struggling to navigate contradictory statutes on whether monarch-friendly plants should be cultivated or banned.

Layered governmental rules continue shifting as monarch conservation competes with lingering weed stigma for milkweeds that still officially populate many municipal restricted plant lists.

Most Conservation Groups Actually Recommend Native Milkweeds

While debate continues simmering around tropical milkweed impacts with reputable experts on conflicting sides, the majority of wildlife conservation organizations strongly advocate planting native milkweed species as optimal for local butterfly populations.

The Monarch Joint Venture, Monarch Watch, National Wildlife Federation, Xerces Society, and most university entomology programs recognize native milkweeds foster healthy monarch reproduction without parasite or behavior concerns generated by tropical varieties. They provide important habitat tailored to regional monarch migration patterns.

These nonprofits offer native milkweed planting guides and advocate for policy changes to eliminate milkweed bans where they remain on the books. Protecting existing native milkweed stands and establishing new ones are top priorities for supporting western monarch conservation.

Key Takeaways on Milkweed Protection for Monarchs

The question of whether to prohibit or actively spread certain milkweed species remains controversial as conservationists debate the best strategies for reversing alarming western monarch declines.

While new bans intend to protect the iconic migratory butterflies, some scientists argue removing tropical milkweed eliminates needed habitat if parasites derive more from climate shifts enabling winter breeding than the non-native plant itself.

Research into these questions continues, but for concerned citizens and policy-makers, most experts currently recommend:

• Planting native milkweeds suitable for your region
• Protecting existing native milkweed stands
• Eliminating pesticide use to prevent milkweed and monarch losses
• Educating others on allowing native wildflowers and milkweeds to grow
• Pushing local governments to overturn old weed rules against beneficial native plants like common milkweed

By fostering more native breeding habitat, migratory fuel sources, and chemical-free zones for endangered western monarchs to feed and reproduce, residents can make an immediate difference while researchers untangle climate change impacts on this beloved butterfly.

Conclusion: Milkweed Essential for Monarch Survival

Milkweeds constitute the only host plant monarch butterflies can utilize to lay eggs and feed caterpillars. With monarch populations in steep decline, milkweed availability has rightfully become a central issue for conservation groups.

But outdated views of native milkweeds as toxic weeds complicate efforts to expand habitat, especially in suburbs and working lands. As monarch researchers debate impacts of non-native tropical milkweed in nurseries, confusion over contradictory public policies places responsibility on average citizens to learn local rules.

While some novelty tropical varieties may pose risks in certain contexts, the general consensus suggests native milkweeds appropriate for regional monarch populations can be planted liberally to support revival of their shrinking numbers. Protecting butterflies requires reversing course on outdated weed policies still common across U.S. cities.

In their struggle for survival, monarch fate has become tied to our capability to restrain habitat loss and provide breeding havens. Working quickly to enact native milkweed-positive statutes while restoring wild areas free of pesticide usage gives us the best chance of preserving vibrant monarch migration for future generations.