The decline of bumblebees
By tracking bee observations over the last 100 years, we can get an accurate picture of bumblebee health in the state. Things don’t look good—the number of bumblebee species has dropped from 11 to 7, with 3 of the 7 (B. fervidus, B. terricola and B. vagans) in danger of being extirpated from the state in the next decade if current trends continue. These losses have the potential to have catastrophic consequences for native biodiversity with cascading impacts across the ecosystem. The diversity of bumblebees impacts the diversity of native plants impacts the diversity of animals utilizing bee-pollinator plants for food, shelter, and nest sites impacts the diversity of predatory animals. Native bee decline is akin to an ecological version of the classic children’s game KerPlunk—eventually our actions will remove too many species and ecosystems will begin to collapse.
To save our bumblebees and other native pollinators, we need to understand the unique set of ecological demands each species requires throughout its life cycle. For bumblebees, these demands include: suitable microhabitats for queen bees to hibernate in the winter and establish nests in early to mid-spring, enough flowering plants for worker production in the late spring to summer, and for the colony to produce sufficient queens and males in mid-summer to fall. Unfortunately, we know little about how and why bumblebee species differ in such demands, limiting our ability to effectively conserve them. Fortunately, the "Bee-cology" Project is filling that knowledge gap by crowdsourcing information about Massachusetts bumblebees. You can get involved by planting a bumblebee-friendly garden and logging your observations.
Planting a bumblebee-friendly garden
All bumblebees need adequate sources of floral nectar and pollen throughout their life cycle in order to keep populations humming. As a group, bumblebees are considered foraging generalists because they can exploit flowers of many different plants. However, each species of bee has a unique set of physical, physiological, and life history characteristics, and flower preferences that must be considered when designing a bumblebee garden. Remember, a truly bumblebee-friendly garden is highly diverse. You need to include appropriate native plant matches for all kinds of bees.
Planting tips
- Remember diversity matters! Bee abundance is not the same as bee diversity; seeing large numbers of bees in your garden is only beneficial if it reflects a large number of different bee species.
- Avoid cultivars of native plants which don’t produce floral nectar. In most plants, you can check for nectar by removing the flower from the base and squeezing it—a bubble of clear liquid means it has nectar. For species with a nectar spur, you can check for nectar by placing a light source behind the flower.
- Avoid pesticide use, particularly those containing neonicotinoids.
- Always avoid exotic plants—they can have dramatic negative effects on bumblebee-native plant relationships and can contribute to bumblebee decline.
- Design plantings to ensure nectar and pollen are available for bumblebees throughout the entire growing season. Create potential nesting and overwintering sites. A dry, protected cavity containing straw, small clumps of moss, and/or dried grass located above or below ground is ideal.
Recommended native plants for bumblebees
Common plant names are provided in this list for easy reference, but always double check the species you purchase is native! Use the "GoBotany" tool to look up if a species is native.
- Aster (Eurybia macrophylla, Symphyotrichum laeve, Symphyotrichum novae-angliae)
- Bee balm (Monarda fistulosa)
- Blue flag iris (Iris versicolor)
- Boneset (Eupatorium perfoliatum)
- Carolina rose (Rosa carolina)
- Common buttonbush (Cephalanthus occidentalis)
- Dogbane (Apocynum androsaemifolium, Apocynum cannabinum)
- Goldenrod (Solidago flexicaulis, Solidago odora, Solidago rugosa)
- Joe-pye weed (Eutrochium maculatum)
- Meadowsweet (Spiraea alba, Spiraea tomentosa)
- Milkweed (Asclepias incarnata, Asclepias syriaca, Asclepias tuberosa)
- Old field toadflax (Nuttallanthus canadensis)
- Spiked lobelia (Lobelia spicata)
- St. John’s Wort (Hypericum canadense, Hypericum punctatum)
- Spotted touch-me-not (Impatiens capensis)
- Swamp thistle (Cirsium muticum)
- Pasture thistle (Cirsium pumilum)
- Turtlehead (Chelone glabra)
- Virginia rose (Rosa virginiana)
- Wild yellow indigo (Baptisia tinctoria)
- Wild raspberry (Rubus occidentalis)