Rare Bee in Chequamegon-Nicolet National Forest

U.S. Department of Agriculture’s Forest Service scientists recently discovered Epeoloides pilosulus, one of the rarest bees in North America, while inventorying bees on the Lakewood half of the Lakewood-Laona Ranger District of the Chequamegon-Nicolet National Forest.

Agency scientists were surveying bees as part of a Great Lakes Native Bee Inventory project funded by the Great Lakes Restoration Initiative (GLRI) when two male Epeoloides pilosulus were captured at Chickadee Barrens in mid-July. A third male was captured the next day. All three bees were netted off black-eyed Susan (Rudbeckia hirta) plants blooming along roadsides in the National Forest.

Epeoloides pilosulus has garnered a large amount of interest because it is considered one of the rarest bees in North America. Though long suspected to be in the Lakewood area, these are the first confirmed records of the species in Wisconsin since 1910 when it was caught in Dane county.

This elusive species is a cleptoparasite of a particular genus of bees (Macropis) which specialize on the collection of floral oils and pollen from plants in the Lysimachia (yellow loosestrife) genus. Abundant Lysimachia plants potentially indicate presence of Macropis bees which in turn would provide evidence of this cuckoo bee. Historically widespread in eastern and central North America, this species was thought to be extinct due to lack of observations until 2002 when Epeoloides pilosulus was rediscovered in Nova Scotia, Canada. A single female was subsequently captured in Connecticut in June 2006.

BugGuide.net, a website which tracks insect observations across the U.S. and Canada, has only one entry (from New York in 2014), and NatureServe, an organization that documents at risk species, admits “Distribution data for U.S. states and Canadian provinces is known to be incomplete or has not been reviewed for this taxon.”

Joan Milam, Adjunct Research Fellow at University of Massachusetts Amherst, confirmed the discovery.

Since 2017, the Chequamegon-Nicolet has been inventorying native bees across the Forest using funds from GLRI. This project has been occurring across the six national forests within the Great Lakes Basin. The bee sampling protocol and identification to species has been aided by David King of the Forest Service’s Northern Research Station and Joan Milam.