Milkweed: Monarch Butterfly Nursery, Spotted Lanternfly Trap?
This is the current state of my front yard, and I absolutely love it.
This is the current state of my front yard, and I absolutely love it. Monarch caterpillars are munching on butterfly milkweed (Asclepias tuberosa), one of the most important host plants for monarch butterflies. It’s not AI, it’s a real image — three large monarch caterpillars chowing down on milkweed leaves, preparing for their journey from egg to chrysalis to butterfly.
Milkweed isn’t just a flower in the garden. It’s the foundation of the monarch butterfly life cycle. Without milkweed, there are no monarchs. In this article, I’ll show you why milkweed is essential for monarch nurseries, how it functions as a chemical defense against invasive spotted lanternflies, and what steps you can take to support pollinators while keeping invasives in check.
Milkweed and Monarch Butterflies: Why It Matters
Milkweed is the only plant that monarch butterflies lay their eggs on. The caterpillars feed exclusively on its leaves, making it a vital monarch butterfly host plant. But the butterflies themselves don’t eat milkweed — they rely on nectar from other flowering plants.
That’s why it’s important to interplant milkweed with pollinator-friendly species like:
Common Boneset (Eupatorium perfoliatum)
Joe-Pye Weed (Eupatorium maculatum & E. serotinum)
Liatris (blazing star)
Coneflower (Echinacea species)
Goldenrod (Solidago species)
Asters (Symphyotrichum species)
also Salvias, Verbena, Coreopsis (Tickseed), Lantana, Pentas, Sedum, Bee Balm, Black‑eyed Susan
These plants attract and provide food for the Monarch butterfly, so planting them with your milkweed will greatly increase the chances of being able to witness this spectacle on your property. Don’t be discouraged if it takes two to three years for your pollinator garden to get established and to begin seeing increased biodiversity. Nurture it and they will come.
From Caterpillar to Chrysalis: The Monarch Life Cycle in Your Garden
Monarch caterpillars don’t form their crysalis on the milkweed plant itself. They will range as far as 30 feet away and ten feet high to find a structure, be it a different plant, or something man-made, that they feel is sturdy enough to protect and support them for the roughly two weeks that they are transforming. In this example, she chose a large established sage plant that was right next to the milkweed.
They attach a very tough, sticky patch of silk first, then use an apparatus on their hind-end called a cremaster to hook into that patch. Then they do a really big situp and fold themselves down as they transform. Can you see the spot where the caterpillar above is beginning to bend, she is simultaneously changing color?
Notice the drastic changes in only three days. The crysalis is notably smaller, and has changed color dramatically. The yellow is all gone, and you can now clearly see the oxygen exchange ports, which appear as gold dots, or trim, as I like to think of it. It appears quite regal and delicate.
As I write this, the crysalis above is only at day 6 of metamorphosis. I will continue to monitor her progress and update with another post or a series describing the entire process.
Milkweed’s Chemical Defenses: A Natural Barrier to Pests
Milkweed is more than just a beautiful wildflower though. It’s a chemical fortress. Inside its leaves and stems, it carries a potent arsenal of cardenolides, a class of toxic cardiac glycosides. These compounds are designed by the plant to deter herbivores by interfering with a key cellular engine: the sodium-potassium pump (Na⁺/K⁺-ATPase) found in animal cell membranes. When this pump is disrupted, nerves misfire, muscles spasm, and the heart can seize.
For most insects, especially opportunistic feeders like the spotted lanternfly (Lycorma delicatula), this is a death sentence. The lanternfly’s gut and nervous system are not adapted to neutralize or store cardenolides safely. Within hours of ingesting milkweed, the toxins begin to overwhelm its physiology, leading to paralysis and death. In short, milkweed is not just an unpleasant snack, it’s a biochemical trap for the lanternfly.
Monarch butterflies (Danaus plexippus), however, have evolved alongside milkweed over millions of years in a different arms race. Monarch caterpillars not only tolerate milkweed’s toxins, they’ve developed molecular “resistance” at the pump level. A few key mutations in their sodium-potassium pump alter its structure just enough that cardenolides no longer bind effectively. This means the poison simply doesn’t work on them the way it does on other insects.
Rather than flushing the toxins out, monarchs keep them. As caterpillars, they store cardenolides in their tissues. When they metamorphose into butterflies, those toxins remain, making them distasteful or even poisonous to predators like birds. The plant’s weapon becomes the monarch’s shield.
The result? Milkweed stands as both a nursery for one of North America’s most iconic butterflies and a lethal barrier to an agricultural pest.
Milkweed Isn’t the Fix: How to Fight Spotted Lanternfly
The problem is, spotted lanternflies rarely choose milkweed as a host. They may probe it and move on, because it isn’t among their preferred foods (they go hard for tree-of-heaven, grapevines, maples, black walnut, etc.).
Protecting our ecosystems means cutting off that preference and their pathways: remove or treat tree-of-heaven (use it as a professionally managed “trap tree” where recommended), diversify plantings, and inspect vehicles, firewood, yard equipment, and outdoor gear before you move them. Kill what you can, when you can. Crush nymphs and adults; scrape egg masses into alcohol/hand sanitizer; drop live bugs into soapy water, and use wildlife-safe circle traps rather than bare sticky tape.
Report sightings to your state extension or agriculture department and follow local quarantine rules to avoid spreading them. Where infestations are heavy, targeted, pollinator-safe treatments on trap trees by licensed professionals can help; broad, indiscriminate spraying harms the very insects we’re trying to support. On the broader front, agencies and researchers are scaling monitoring, quarantine enforcement, and biological controls (including entomopathogenic fungi and egg-parasitoid wasps) to keep pressure on this invader without collateral damage.
Learn, Plant, Protect: A Local Defense Strategy
The strongest defense against any threat: lanternflies, other invasives, disease, pollution, is ecological literacy at home. Learn your place – know which plants, insects, birds, and fungi belong in your county and when they’re supposed to be there. Then back them up.
On any property you manage, build a sanctuary that serves your local food web: plant regionally native species (trees, shrubs, forbs, grasses), stagger blooms and seed, leave leaf litter and stems for overwintering, provide clean water and dark nights, and keep chemicals out. Join local native-plant and watershed groups, pay attention to extension bulletins, and report unusual sightings.
When more of us recognize what’s normal and actively support it, early problems get caught, healthy systems recover faster, and our yards stop being liabilities, they become habitat that pushes back.
