County Extension offices frequently hear from home gardeners who have questions about tropical milkweed plants and milkweed bugs.
Tropical milkweed plants are a non-native landscape favorite because they serve as a host plant for monarch and queen butterfly larvae. They are easy to grow and often are found in children’s butterfly gardens.
Tropical milkweed’s colorful red and orange flowers – along with its long growing and blooming season – make this a great plant for beginner gardeners.
While the plant — Asclepias currasavica — is popular, milkweed bugs are often found on it.
Milkweed bugs are orange and black, and they are considered a nuisance pest of tropical milkweed. Sometimes milkweed bugs are mistaken for a beneficial insect called the milkweed assassin bug.
When milkweed bugs infest tropical milkweed, gardeners can be unsure about what to do. Should they treat the bugs – which could harm butterflies and beneficial organisms – or leave them alone?
Handpick milkweed bugs
Cutting off the tops of plants won’t eliminate these insects, as they may come back. But handpicking them off the plant is an effective way to control them and handpicking doesn’t involve the use of pesticides.
If you’re not squeamish, you can handpick— knocking them into a bowl of soapy water. Leave them there for a little while. Then pour out the water and dead bugs.
Remove the seed pods
Interestingly, although milkweed bugs can feed on plants, they primarily feed on milkweed seed pods. Remove seed pods if you have them. This is an easy way to help control milkweed bug populations.
Knock them off with a jet of water
Another strategy for dealing with milkweed bugs is to knock the bugs off the plants with a strong spray of water from the garden hose. You might need to do this for several mornings in a row to get some control and then check back every two or three days after that. It is a pesticide-free way to reduce pests.
Leave the pests alone
Though it’s distressing to see them on the milkweed, they are harmless.
Milkweed bugs and aphids infest tropical milkweed in stages. Sometimes, there are a lot of them. Other times, they’re gone.
Many butterfly gardeners simply ignore the milkweed bugs and aphids – knowing their populations are cyclical and they usually don’t kill the plant. These gardeners tolerate some plant damage in exchange for not using pesticides on plants preferred by butterflies and other beneficial insects.
If you don’t want to remove them, just let them be. In time, they will move on. However, they may be repeat visitors to your milkweed plants.
Plant native milkweeds
Our native milkweeds typically have less pest problems. Consider planting native milkweeds in your landscape. These plants have pink to white flowers. Learn more about native milkweeds and visit a local native plant nursery, check out the Florida Museum of Natural History butterfly brochures or contact your local Extension office.
Another benefit of native milkweeds is they die back naturally in the winter here in Florida. This natural dieback may result in less parasites that can infect monarch larvae. However, you can simulate this with tropical milkweed by cutting them back in winter, on or around Thanksgiving.
These references, which were used for this column, offer additional details:
University of Florida. Florida Museum of Natural History Butterfly Brochures. Retrieved from https://www.floridamuseum.ufl.edu/discover-butterflies/brochures/.
University of Georgia. Bugwood website. Milkweed bug insect images. Retrieved from https://www.insectimages.org/search/action.cfm?q=milkweed+bug.
Nicole Pinson is the Urban Horticulture Agent in Hillsborough County. Laura Barber and Jan Ignash, master gardener volunteers contributed to this column.
Published September 15, 2021