The Rusty Patched bumble bee

Late in the 1990s, bee researchers began to notice that the populations of a few bumble bee species were crashing. Within a few years, one of them – the Rusty Patched bumble bee, bombus affinus – seemed to be almost entirely gone.

The Rusty Patched was once common in about 28 states. But by 2016, only a few small, genetically isolated populations could still be found, in parts of Wisconsin and Minnesota (my state); it was estimated that 95% of the bees were gone. The species was on the brink of extinction, with prospects for recovery dim, and the causes of the decline weren’t known. It was declared Endangered and began to receive federal protection.

Since then, there may have been a bit of recovery, although it’s hard to find any reliable numbers. In 2018, a total of 471 rusty patched bumble bees were seen anywhere in the world, and 165 of those sightings were in my state of Minnesota. In 2019 bombus affinus became Minnesota’s State Bee! But 165 bees is a very small number; they’re hanging by a thread.

Despite all of that, in July of 2022, in the middle of a local drought, I spotted what looked like a Rusty Patched in my back yard in Minneapolis, on some Joe Pye weed.

With the plants basically at my back door, and the bees working them steadily, I was able to get some photos. I submitted the first couple to Bumble Bee Watch (www. – a collaborative effort by several universities and conservation groups – and got expert confirmation: not only did I have a Rusty Patched, but it was a male, distinguished by several features including the number of abdominal segments and the cool Mohawk of hair on the top of its head.

And there’s really no mistaking that signature rust-colored patch.

There has to be a colony of Rusty Patched not far from my house. But it’s now August, in an exceptionally hot, dry summer, and the stand of Joe Pye Weed that attracted them is drying up; no bees were on it today. I can only hope that next year bombus affinus will return, and that my back yard can play some tiny part in the recovery of the species.

7 Replies to “The Rusty Patched bumble bee”

  1. To help all pollinators in declining populations it is necessary t o amend the soil to increase its ability to produce protein. Sadly, pollinator experts know nothing, or next to nothing about this issue. Evidence on this matter is contained in “The Albrecht Papers”. Feeding pollinators is not enough. They need to be nourished.
    If you have any interest in this matter, you can contact me. For seven seasons I have had an experimental pollinator garden where the soil has been amended to increase its ability to produce protein.

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