Should Gardeners Remove Milkweed Bugs?

Find out what milkweed bugs and milkweed assassin bugs look like and if you should remove these bugs from your plants when you spot them.

What Does a Large Milkweed Bug Look Like?

14 Nancydietrich Bbxsep20, milkweed bugCourtesy Nancy Dietrich
Immature large milkweed bugs and a monarch caterpillar

“What are these red bugs, and can they harm my butterfly weed plants?” asks Birds & Blooms Reader Nancy Dietrich.

Gardening expert Melinda Myers writes, “These colorful insects are milkweed bugs (Oncopeltus fasciatus) in their immature stage. Adults are flatter, more elongated, and orange and black, and they resemble a boxelder bug. An immature milkweed bug feeds on the plant’s sap and seeds. To get at the sap, it injects a chemical into the plant tissue. This liquefies the tissue, allowing the bug to suck it up.

They don’t cause significant harm to milkweed plants, but gardeners in warmer areas, where the bugs may overwinter, can remove leaf litter and spent stalks to help reduce next year’s population.

Check out the ultimate guide to growing milkweed plants for monarchs.

Should You Remove Milkweed Bugs?

USA, Texas, Hill Country Near Hunt, Small Milkweed Bug...Wolfgang Kaehler/Getty Images
Adult large milkweed bug

Birds & Blooms contributor Jill Staake says it’s not necessary to eliminate milkweed bugs. “Milkweed bugs might seem like an annoyance, but they rarely cause enough damage to plants to be an actual problem,” she says, mentioning that they are “completely harmless” to monarch caterpillars and butterflies.

If you’d still rather not have a single milkweed bug on your milkweed, there are a few options you can try. First, you can always pick them off by yourself. As Melinda said, you can also eliminate leaf litter where the bugs overwinter. Jill also recommends “a strong squirt from the garden hose.” It is imperative to stay away from insecticidal methods or chemicals, as those methods might harm monarchs. Instead, stick to natural pest-control solutions like those mentioned above.

Meet the milkweed tussock moth and caterpillar.

Milkweed Bugs vs Milkweed Assassin Bugs

Milkweed Assassin BugJoann Bristol/Getty Images
A milkweed assassin bug sits on orange flowers of a milkweed plant.

Despite the similar names, the milkweed bug and milkweed assassin bug (Zelus longipes) are different insects. Milkweed bugs are herbivorous and feed only on milkweed plants. Assassin bugs are carnivorous, feeding on other insects. Although the name sounds scary, humans don’t have a whole lot to fear from milkweed assassin bugs. They won’t cause damage to gardens, and sometimes, they might even take out other pests that gardeners dislike.

“Milkweed assassin bugs do eat monarch caterpillars, but they also eat a large variety of other insects, many of which are considered garden pests,” Jill Staake explains. (Psst—watch out for these monarch butterfly predators and parasites). “It’s generally best to let nature take its course, unless you don’t have any surviving caterpillars at all.” If that’s the case, Jill says you can remove the bugs by hand — but wear garden gloves, because the bugs occasionally bite.

Next, learn how to tell the difference between monarch eggs and aphids.

Popular Videos

Emily Hannemann
Emily Hannemann is an associate digital editor for Birds & Blooms. She has a bachelor’s degree in English and a master’s degree in magazine writing from the University of Missouri - Columbia. When she’s not writing and editing, you’ll find her swimming, running, or hiking. She knows blue jays are controversial, but she loves them anyway.