06/27/2023
Tropical milkw**d - the milkw**d you SHOULDN'T grow!
You may have heard that you can help save the iconic and endangered monarch butterfly by growing its only host plant, milkw**d. However, not all milkw**d species are made equal, and there’s one in particular that should never be planted outside of its native range. Tropical milkw**d (Asclepias curassavica) is native to Mexico but was introduced to the US because of its attractive red blooms and status as a monarch host plant. It quickly escaped cultivation and is now labeled as an invasive species, but the damage caused by tropical milkw**d is even deeper than that.
Have you ever seen a butterfly born with crumpled wings that never expanded? It was likely caused by a protozoan parasite. Ophryocystis elektroscirrha, or OE, is linked to multiple health and migration issues, transferring from monarch butterfly wings to milkw**d leaves. Caterpillars become infected when they emerge and eat those leaves. Luckily, when infected milkw**d plants die back, the parasite dies with it. Unlike our native milkw**d species, tropical milkw**d is often evergreen in temperate regions, meaning OE is able to survive, multiply, and infect the next generation of monarchs. In northern parts of the US, tropical milkw**d blooms extremely late into the year, confusing the monarch butterflies to breed instead of migrating south.
You can support monarchs and other pollinator species by growing the host and nectar plants native to your state and county. If you live in Virginia, toss the tropical milkw**d and opt for swamp milkw**d (A. incarnata), common milkw**d (A. syriaca), or butterfly w**d (A. tuberosa) instead!
Photo © 2016 Jee & Rani Nature Photography (License: CC BY-SA 4.0)