Plants and Animals
Bombus sandersoni Sanderson's bumble bee
Key Characteristics
Bombus sandersoni is a relatively small bumble bee, with queens ranging from 15-17 mm, workers 10-14 mm, and males 12-15 mm. Queens, workers, and males have similar hair color patterns. Abdominal segments T1-2 are yellow, T3-4 are black, and T5 is either black, yellow, orange-brown, or white (rare, queens only). T6 (males only) is black, yellow, or black with some yellow hairs intermixed. The dorsal side of the thorax often has a black band between the wings. The face and top of the head are black in workers, yellow in males, and variable in queens. The Sanderson’s bumble bee is often mistaken for the half-black bumble bee (Bombus vagans) due to their similar color patterns. Microscopic characteristics of B. sandersoni that distinguish it from B. vagans include a cheek length that is as long or just shorter as is broad and, in males, antennal segments A3-4 with black hairs and A5-12 without (Williams et al. 2014).
Status and Rank
US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: S2S3 - Rank is uncertain, ranging from imperiled to vulnerable
Occurrences
| County | Number of Occurrences | Year Last Observed |
|---|---|---|
| Alger | 4 | 2024 |
| Baraga | 1 | 2023 |
| Chippewa | 1 | 2021 |
| Delta | 3 | 2020 |
| Gogebic | 3 | 2019 |
| Houghton | 3 | 2023 |
| Iosco | 1 | 2018 |
| Iron | 3 | 2020 |
| Kent | 1 | 2021 |
| Mackinac | 1 | 2020 |
| Ontonagon | 2 | 2019 |
| Oscoda | 1 | 2017 |
| Schoolcraft | 2 | 2021 |
Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Habitat
The Sanderson’s bumble bee can be found in wooded areas. Known foraging resources include sweet clovers (Melilotus spp.), bergamot (Monarda spp.), brambles (Rubus spp.), and honeysuckles (Lonicera spp.), among other species (Colla and Dumesh 2010, Williams et al. 2014).
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Management Recommendations
This species has recently experienced declines throughout its historic range (Colla et al. 2012). Multiple stressors can be blamed for this decline, including the spread of pathogens from commercial bumble bee colonies used in greenhouses (pathogen spillover), widespread use of neonicotinoids, a pesticide group that is highly toxic to bees, and habitat loss due to an increase in agriculture and urbanization (Colla and Packer 2008, COSEWIC 2010, Grixti et al. 2009). Conservation efforts should center around preserving natural habitat patches, promoting reestablishment of native wildflowers, and reducing the use of pesticides and herbicides.
Active Period
Flight from first week of May to fourth week of September
Survey Methods
Surveys typically involve capturing foraging bumble bees with an aerial net and identifying the individual species (Colla and Packer 2008, Grixti et al. 2009).
Aerial net
Survey Period: From first week of May to fourth week of September
Time of Day: Daytime
Visual survey
Survey Period: From first week of May to fourth week of September
Time of Day: Daytime
References
Survey References
- Colla, S.R. and L. Packer. 2008. Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379-91.
- Grixti, J.C., L.T. Wong, S.A. Cameron and C. Favret. 2009. Decline of bumble bees (Bombus) in the North American Midwest. Biological Conservation 142: 75-84.
Technical References
- Colla, S.R. and L. Packer. 2008. Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379-91.
- Colla, S.R. and S. Dumesh. 2010. The Bumble Bees of Southern Ontario: Notes on Natural History and Distribution. Journal of the Entomological Society of Ontario 141:38-67.
- Colla, S.R., F. Gadallah, L. Richardson, D. Wagner, and L. Gall. 2012. Assessing declines of North American bumble bees (Bombus spp.) using museum specimens. Biodiversity and Conservation 21(14): 3585-3595.
- COSEWIC. 2010. COSEWIC assessment and status report on the Rusty-patched Bumble Bee Bombus affinis in Canada. Commitee on the Status of Endangered Wildlife in Canada. Ottawa. 34pp.
- Grixti, J.C., L.T. Wong, S.A. Cameron and C. Favret. 2009. Decline of bumble bees (Bombus) in the North American Midwest. Biological Conservation 142: 75-84.
- Williams, P.H., R.W. Thorp, L.L. Richardson, and S.R. Colla. 2014. Bumble bees of North America: an identification guide. Princeton University Press.