The rusty patched bumblebee (scientific name Bombus affinis), is a fuzzy, loveable bee that has experienced precipitous declines in recent years. It used to be a common bumblebee in the eastern United States, but sometime around the late 1990’s, the range of this species contracted to a fraction of where it used to occur. Nowadays, rusty patched bumblebees are largely limited to an area in the Midwest, occurring in Minnesota, Iowa, Wisconsin, and Illinois. In 2017, the rusty patched bumblebee was listed as an endangered species, making it the first endangered bee in the continental United States.
I am lucky enough to live in St. Paul, Minnesota, one of the places where rusty patched bumblebees can still be reliably found. This past spring and summer, I set out to find as many of them as I could, and I spent over a hundred hours searching for rusty-patched bumblebee around my neighborhood.
Even though rusty patched bumblebees are generalist foragers who visit a wide variety of flowers for pollen and nectar, they have certain flowers that they like best. I noticed that what I was seeing didn’t entirely match up with the official list of recommended plants. This isn’t too surprising, as researchers in the UK recently found that recommended plant lists often don’t do a great job matching up with what bees actually visit.
Before I get to the plants, it’s worth noting this list is not strictly scientific, as it’s more a compilation of my wanderings throughout my neighborhood. This means that my observations were mostly limited to plants people planted in their gardens, so there could be other flowers that rusty patched bumblebees really love but I wouldn’t know since they aren’t planted in my neighborhood. Lastly, I want to give a special thanks to my friend Ian Lane for helping identify the tricky plants.
So what plants did I find the rusty patched bumblebee on? Here’s the list:
1. Scarlet beebalm
Scarlet beebalm (Monarda didyma) was far and away the favorite plant for rusty patched bumblebees in my neighborhood. It was one of the few plants where the rusty patcher could be reliably found, day after day. In some big garden patches, I saw as many as five at a time (as well as many other bee species). Even near the end of bloom, when only a handful of scarlet beebalm flowers were left, I would see rusty patched bumblebees ignore other flowers to feed on the handful of remaining flowers.
2. Bee balm (aka wild bergamot)
Though not quite as attractive as Scarlet beebalm, regular bee balm (Monarda fistulosa) also proved attractive to rusty patched bumblebees. There were some gardens that had regular bee balm and scarlet beebalm planted side by side, and the rusty patched bees almost invariably preferred the scarlet one. That said, regular bee balm was a fan favorite of many different species o bumblebee, not just the rusty patched.
3. Giant hyssop
Giant hyssop (Agastache spp.) covers a bunch of different species and varieties, almost all of which seem to be beloved by bees. If you plant it, it is essentially guaranteed to be continuously covered in many different species of bumblebees. One particular strength of these plants is that most varieties seem to bloom for long periods, providing beautiful flowers and forage all summer.
4. Joe-Pye weed
Joe-Pye weed (Eutrochium spp.) also includes multiple plant species, and it is a total bee magnet, attracting endless big and small bees in addition to the rusty patched bumblebee. Be careful though, since this plant can grow big!
5. Obedient plant
Obedient plant (Physostegia virginiana) may not attract as many bumblebees as the other plants on this list, but they make up for it by attracting many small- and medium-sized bees. They also demonstrate some of the limits of my list, since there was only a single spot in my neighborhood that had any obedient plant growing. However, in that one little spot, rusty patched bumblebees could be consistently found.
Honorable mention: Phlox
One of the most common flowers in the neighborhood was Phlox (almost all of it was garden phlox, or Phlox paniculata). However, rusty patched bumblebees didn’t seem to like it and didn’t visit it much. I only saw rusty patchers visiting it after most of the bee balm was done blooming. For most of the summer, I didn’t see any bees visiting it at all, to the point where I wasn’t sure if it even offered nectar. For that reason, phlox only merits an honorable mention; seems like the bees aren’t a huge fan, but it’s better than nothing.
Dishonorable mention: Spotted knapweed
One flower the rusty patched bumblebee really likes is spotted knapweed (Centaurea stoebe). Unfortunately, this plant is invasive in the US, and if left unchecked, can totally take over an area. Luckily, at least in my neighborhood, spotted knapweed was only present in a few heavily disturbed areas in vacant lots and by railroad tracks. However, spotted knapweed illustrates a difficult paradox of bee conservation; sometimes the flowers bees prefer are attached to invasive and harmful plants that can potentially harm the broader ecosystem. As a result, I don’t recommend planting spotted knapweed. Though if you do remove it, make sure to plant something else that bees like.
If you’re looking to attract some rusty patched bumblebees, you should try planting some of the plants on this list. Even if that species doesn’t occur in your area, these plants will still attract loads of excellent bumblebees and other native bees. But don’t limit yourself to this list because there are many other excellent, bee-friendly flowers out there. Just remember, it’s best to stick to plants that are native to your area and to avoid ornamental varieties that don’t have good pollen and nectar.
I was surprised that scarlet beebalm and obedient plant weren’t on the official list of recommended plants for the rusty patched bumblebee from the US Fish and Wildlife Service. It just shows that there are still many gaps in what we know about which plants the rusty patched bumblebee likes best. We also don’t know much about what plants queens use in the early spring. Therefore it’s best to plant a variety of flowers and see what the bees like. One important thing to keep in mind is you want to have a succession of plants that bloom throughout the season. Early spring and late summer are especially important times for bumblebees when there can be a shortage of good flowers.
Importantly, if you want to help save the bees, don’t keep a honeybee hive. Honeybees aren’t native to North America, they aren’t in danger of going extinct, and they can compete with native bees and infect them with pathogens. If you want to learn more about that topic, check out this article in Scientific American. Unlike honeybees, we know the rusty patched bumblebee is in trouble and needs our help. You can help by not using any pesticides and planting native plants. Finally, if you see a rust patched bumblebee, consider snapping a picture and submitting it to iNaturalist. There’s still so much we don’t know about their basic biology, including where the bee still occurs, their preferred nesting sites, and what plants they like best.