Sustain Our Nation's Forests and Grasslands

One of the rarest bees in North America, discovered thanks to Great Lakes Native Bee Inventory

A rare bee specimen
A rare bee, Epeoloides pilosulus, was positively identified by Joan Milam, adjunct research fellow at University of Massachusetts Amherst. Photo courtesy of Joan Milam.

WISCONSIN – This summer, scientists with the USDA Forest Service made a remarkable discovery on the Lakewood half of the Lakewood-Laona Ranger District of the Chequamegon-Nicolet National Forest – two male Epeoloides pilosulus at Chickadee Barrens, followed by a third male at the intersection of Mountain Lakes Road and Forest Road 2296. All three bees were netted in mid-July, 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 found and identified in Dane county.

This elusive species is a cleptoparasite of a particular genus of bees (Macropis) which specializes 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.”

The Chequamegon-Nicolet National Forest’s Native Plant and Pollinator Program Crew made the discovery as part of the Great Lakes Native Bee Inventory multi-year project funded by the Great Lakes Restoration Initiative.

“What a success for the Great Lakes Native Bee Inventory GLRI project and for the NP3 Crew who has been hard at work netting bees across the East Zone this spring and summer whenever the weather cooperated. Hats off to Crew Leader Nick Gremban and Crew Members Chelsea Camp, Emily Colson, and Hunter Paplham for confirming long-held suspicions by nabbing this special bee species,” stated Biological Science Technician Nicole Shutt, who passionately leads the NP3 Crew.

Nicole has overseen opportunistic netting targeting specific flower species in order to make this type of incredible discovery, and she happened to be in the office compiling bee data on the two days the Crew netted Epeoloides. Nick Gremban remembers netting the third male: “We stopped at a large patch of Whorled Loosestrife (Lysmachia quadrifolia) to see if we could net Macropis off the plants. After not seeing much, I wandered down the road and discovered a patch of Black-eyed Susan where I spied a couple of small bees nectaring from the plants.  Instinctively, I caught both and then walked back to where the rest of my crew was netting, not realizing I captured one of North America’s rarest bees!”

In addition to the Epeoloides pilosulus discoveries was another rare bee and WI State record netted by the NP3 Crew off Black-eyed Susan on the same day as the first E. pilosulus males: one female Holcopasites calliopsidis, a cleptoparasite of the Playground Bee (Calliopsis andreniformis) which nests in sandy, compacted soils, was captured along Jack Pine Camp Road. These discoveries show the benefit of targeted surveys and the benefit of keeping non-native, invasive plants off our national forest roadsides so our native plants, and the bees who depend upon them and each other, can thrive.

The NP3 Crew will continue netting bees through September. Joan Milam, Adjunct Research Fellow at University of Massachusetts Amherst confirmed the discoveries and stated, “Who knows what other treasures we will find in those samples?”

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.