Massachusetts bumblebees are in trouble

This follows a trend of declining bumblebees in the northeast US

Zach Portman
7 min readSep 7, 2021


There are about 50 species of bumblebee in the US and Canada, and over the last decade, it has been well documented that multiple species of bumblebee are declining. However, the picture is complicated, with some species declining, some increasing, and other species lack the data to know one way or the other. It also varies by region, since some declining bumblebees are still doing okay in certain areas of their range. As a result, bumblebees in some areas seem to be doing much better than others.

So how are bumblebees doing in Massachusetts?

Starting approximately 100 years ago, scientist Otto Plath (also notable for being the father of poet Sylvia Plath), conducted an in-depth investigation of the bumblebees of Massachusetts. Based at Harvard’s Arnold Arboretum, he excavated and studied hundreds of bumblebee nests and exhaustively documented the biology of the different species. He published his work in various scientific journals, and then finished with his magnum opus, the 1934 book “Bumblebees and Their Ways.”

As a result of that book, there is a fairly complete picture of how common different bumblebee species were in Massachusetts back in the period spanning 1921 to 1933, when Plath did most of his research. This research can be used to see how the historic bumblebees compare to the present day. From that record, one thing is clear — Massachusetts bumblebees have undergone some big changes, and they’re mostly bad.

Bombus affinis, the rusty patched bumblebee
The Rusty-patched bumblebee (Bombus affinis) used to be common in Massachusetts but not it no longer occurs in the state.

In total, Otto Plath documented 13 different bumblebee species in the vicinity of Boston. By comparing them to more than 8000 recent observations on the community science platform iNaturalist, we can get a rough idea of how they’ve changed, particularly whether any of the species he reported are no longer around, or if species that were previously common have become rare.

Here are how the 13 species Plath documented are doing now:

  1. Bombus affinis, the Rusty patched bumble bee. Status: Extremely Bad. Plath reported this to be one of the more abundant bumblebees, describing it as a “common” species and he reported finding 66 nests. In recent times, the rusty patched bumblebee has…



Zach Portman

I am scientist who studies bees. My research covers the identification, biology, evolution, and conservation of native bees.