Fading Out: Are Monarchs a Thing of the Past?

Monarchs. You know them, but will your grandchildren? These once common creatures are rapidly disappearing. Since the 1980s, 99.4% of the western monarch population has disappeared. Scientists have been acutely aware of this decline for decades, but it wasn’t until the Xerces Society for Invertebrate Conservation’s shocking annual survey results were released this January that the public took notice. Only 28,429 monarchs were counted at 213 sites in California – an astounding 86% drop from last year’s count. It’s official – our western monarchs are in decline, and the neighboring eastern population isn’t doing much better; their population has declined over 90% since 1996.

So, what is the cause?

Scientists attribute the decline to a multitude of factors, including migratory disruptions, urban sprawl, and the use of chemicals on corn and soybean crops, but they all lead to one overarching outcome: habitat degradation.

Monarchs rely exclusively on milkweed to lay their eggs and sustain their offspring until they can metamorphize into butterflies. They use both tropical and native milkweed plants to procreate, but the former can cause more harm than good. Before the introduction and widespread use of tropical milkweed, the deciduous nature of native milkweed would force monarchs to migrate southward in search of fresh leaves, ultimately protecting them from the oncoming winter temperatures of their northern homes. But with tropical milkweed’s year-round leaves, monarchs miss the signals communicating that they need to move south, leading to catastrophic mortalities.

Native milkweed (Asclepias fascicularis, or narrow leaf milkweed), and a monarch feeding

If that isn’t bad enough, the perennial leaves of tropical milkweed do not offer the same resources as the native variety. Normally, feeding caterpillars absorb cardenolides, the protective compounds found in milkweed that naturally ward off a lifetime of parasites and predators. But the prolonged atmospheric exposure of these year-round leaves ends up breaking down cardenolides, which ultimately decreases the monarch’s defenses and lifespan.

Another problem is the destruction of flowering plants and milkweed. We’ve sacrificed natural landscapes and their biodiverse habitats for cities, suburbs, and monocultural farms producing ethanol, hydrogenated oil, and high-fructose corn syrup. Besides the obvious habitat loss due to urban development, the agricultural implications are astounding. Ever since Monsanto introduced “Roundup Ready” crops, which are genetically modified to be highly resistant to glyphosate, the most widely used herbicide worldwide, populations of milkweed and other pollinator plants have declined drastically. Today, 95% of corn and soybean grown in the U.S. are Roundup Ready crops – meaning food producers nationwide use copious amounts of glyphosate to remove anything that is not their desired crop. Milkweed habitat loss due to glyphosate is now estimated to exceed 100 million acres.

So what does all this habitat degradation mean? It means monarchs aren’t the only ones in trouble. Their declining numbers serve as a warning about the health of our lands. Some are likening monarchs to the formidable relationship between canaries and coal mines, dubbing them “the Canary in the Cornfield”: representing terrifying declines in pollinator populations; highlighting legitimate concerns about agricultural safety and sustainability; and potentially even foreshadowing a food chain collapse. According to researchers at UC Berkeley, one of every three bites of food depends on pollinators. Does that mean their food scarcity today is our food scarcity tomorrow – and if so, what can we do about it?

Unfortunately, changing or reducing urban sprawl, chemical use, and climate change on an individual level would be like trying to put a genie back in the bottle. But here is what you can do:

  • Plant native milkweed and flowering plants to create pollinator islands, and if you already have tropical milkweed, cut back vegetation between October and February to spur regrowth.
  • Support sustainable farming by purchasing locally grown and/or organic produce.
  • Treasure monarchs while you can and use them as a living a reminder that our land and its creatures are finite and fragile.


“We do not inherit the earth from our ancestors; we borrow it from our children.”

– Chief Seattle