05/16/2026
For about twenty years, the well-intentioned advice from butterfly gardeners across the Southeast was the same: plant milkw**d for the monarchs.
And the milkw**d that nurseries actually carried — the bright orange-and-yellow showstopper available at every garden center — was tropical milkw**d, Asclepias curassavica. It grew fast.
It bloomed all year. Monarchs flocked to it. What we now know is that it was quietly making things worse. In June 2025, the Florida Invasive Species Council (FISC) officially classified tropical milkw**d as a Category II invasive species across all regions of the state — north, central, and south.
The University of Florida's IFAS Assessment lists it as invasive throughout Florida and explicitly not recommended. The Florida Association of Native Nurseries (FANN) updated its 2025-2026 ethics policy to flag tropical milkw**d for removal from member inventories, and UF Extension's current recommendation is to inspect plants for active monarch caterpillars and, if none are present, remove the plant entirely.
The reason is biological. Tropical milkw**d doesn't go dormant in Florida winters the way the state's 21 native milkw**d species do. It keeps growing year-round. And monarchs that find it growing in January don't migrate — they stay, breed locally, and accumulate massive parasite loads of Ophryocystis elektroscirrha (OE), a protozoan that deforms wings, shortens lifespan, and prevents emergence from the chrysalis.
The plant that gardeners thought they were providing as a butterfly buffet was effectively trapping monarchs into a year-round disease cycle and breaking the migration that defines the species.
Florida has 21 native milkw**d species, and three are commonly available through native plant nurseries: swamp milkw**d (Asclepias incarnata), with pink flowers and a love of damp ground; aquatic milkw**d (Asclepias perennis), with white flowers for wet or partly shaded sites; and butterfly w**d (Asclepias tuberosa), with brilliant orange blooms for sunny, well-drained spots. All of them go dormant in winter. None of them harbor OE the way tropical does.
None of them disrupt migration. If you have tropical milkw**d in your garden right now, the current guidance is straightforward: remove it (after checking for active caterpillars) and replace it with one or more of the 21 native species. The intentions were always good. The science has just caught up.
