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Oregon Bee Atlas: wild bee findings from 2019

Lincoln Best1*, Joseph D. Engler2, Cody Feuerborn1, Jen Larson1, Briana Lindh3, Christopher J. 
Marshall4, Sarah Kincaid1 , Andony Melathopoulos1 , Samuel V.J. Robinson5 

* Corresponding author: Lincoln.Best@oregonstate.edu
1 Department of Horticulture, Oregon State University, 4017 Agricultural and Life Science Building
     Corvallis, Oregon, USA 97331-7304
2 35133 SE Homan Road, Gresham, Oregon, USA 97080
3 Department of Biology, Willamette University, Olin Science Center, 900 State Street, Salem, Oregon, USA 97301
4 Department of Integrative Biology, Oregon State University 3029 Cordley Hall, Corvallis, Oregon, USA 97331-7304
5 Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada

Cite this work as: 

Best, L., J. D. Engler, C. Feuerborn, J. Larsen, B. Lindh, C. J. Marshall, A. Melathopoulos, S. Kincaid, S.V. J. Robinson. 2022. 
Oregon Bee Atlas: Wild bee findings from 2019. Catalog of the Oregon State Arthropod Collection. 6(1): 
1—13. DOI: http://dx.doi.org/10.5399/osu/cat_osac.6.1.4906.

Abstract

The Oregon Bee Atlas is a new volunteer-led effort to characterize the bee fauna of Oregon State by 
collecting, preparing, and databasing specimens of wild bee species and their plant host records. In 
2019, volunteers submitted 25,022 bee specimens across all Oregon counties, representing 224 unique 
bee species and 45 unique bee genera. Specimens were collected from a total of 352 unique flowering 
plant genera, resulting in the largest contemporary state-level database of bee-host plant interactions. 
Volunteers produced valuable occurrence records for species poorly known for the state, and species 
of conservation concern. The 2019 data builds on the efforts of 2018 in demonstrating the power of a 
specimen-focused, volunteer wild bee survey.

Introduction

Beginning in 2018, the Oregon Bee Atlas has been generating museum-quality bee specimens for 
the state of Oregon (Best et al., 2021). The Oregon Bee Atlas (OBA) is a volunteer-focused initiative 
to survey the bee fauna of Oregon.  The mission of the OBA is to train and equip citizen scientists 
to: (a) create and maintain a comprehensive, high quality and publicly accessible inventory of 
the state’s wild bees and their plant-host preferences, (b) to educate Oregonians on the state’s bee 
biodiversity, and (c) to conduct an on-going survey of wild bee populations to monitor their health. 
Started in 2018 by Oregon State University (OSU), Oregon Department of Agriculture (ODA), and 
Oregon Department of Forestry (ODF), the OBA was established as a response to the general lack of 
knowledge about the status of Oregon’s wild bees. 
 
Through the framework of the OBA, volunteers receive the necessary training to collect and prepare 
bee specimens and to upload their records through a centralized and standardized database. 
Volunteers are partnered with expert taxonomists and database managers to ensure quality records 
are created and maintained. All observational records generated by the OBA are based on identified 



Catalog: Oregon State Arthropod Collection   Vol 6(1) 1—13 

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specimens with voucher specimens deposited in the Oregon State Arthropod Collection (OSAC) so 
that identifications can be confirmed into the future and used as comparative reference material.  All 
records are made publicly available.

Here we represent the findings from the second year of the OBA, including a review of the spacial 
distribution of sampling, the species detected, and notable wild bee discoveries. 

Methods

Methods used in 2019 follow those described in Best et al. (2021), with some minor changes.  

Volunteers
Volunteer recruitment continued through presentations to OSU Master Gardeners, Master 
Naturalists, and local beekeepers. Recruitment was assisted because of the release of a documentary 
featuring the Oregon Bee Atlas on March 29, 2019, through the Oregon Public Broadcasting series 
Oregon Field Guide (https://www.opb.org/news/article/oregon-bee-atlas-project).  We conducted 
eight trainings consisting of 101 students which were held in the cities of Corvallis, Grants Pass, La 
Grande, McMinnville, Mosier, Portland (x2), and St Helens. Training took place between November 
2018 and March 2019 and in most instances training events lasted one full day.  Topics covered at 
training events included: project background, bee biology, insect collection and specimen preparation, 
and data entry. Two additional five-day taxonomy courses were held on July 8—12 and 15—19, 2019 
that covered genera-level identification of most common wild bees in Oregon, with species-level 
identification for bumble bees.  

Sampling methods and effort 

Unlike 2018, volunteers in 2019 only conducted undirected, free sampling, and directed sampling 
used the previous year. The reason directed sampling was dropped in 2019 was to better address 
the tasks of the Oregon Bee Atlas at this stage, namely, to detect bee species and delimit their range 
in Oregon. As described in Best et al. (2021), bees were primarily collected using a variable transect 
aerial netting, with a small subset collected using trap nests, blue vane, or pan traps (see Westphal 
et al. 2008 for description of each method). Volunteers conducting aerial netting were encouraged to 
pool bees sampled from each host plant and to separate those samples into killing jars to document 
the association of the bees with the host plant. In all cases, however, all sampling conducted within 
a 1 ha radius of where sampling started was pooled together into a common sample (e.g., aerial 
netting from a given plant host species growing within a 1 ha area were pooled). All bees caught from 
a collector within this 1 ha unit, at a given date and time, and where applicable, from a given plant, 
were provided with a unique identifying number (Sample ID). 

Observational data entry, specimen preparation and labeling

As in 2018 (Best et al. 2021), volunteers recorded the following core data: (a) full name of collector, (b) 
a Sample ID identifier, (c) the date and time when sampling was initiated, (d) the name of the closest 
geographic or civic landmark to the sampling area, (e) latitude and longitude coordinates in degree 
decimal format, and (f) the number of bees collected. For volunteers installing traps the date and time 
that traps were removed was also included and when netting was conducted from a specific host 
plant, the family, genus, and species of the host plant was recorded. Beginning in 2019, volunteers 
were provided the option of generating plant host names using fields in iNaturalist (see below).  



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Volunteer data continued to be recorded using two methods, namely written notebooks or using 
iNaturalist, although volunteers were strongly encouraged to use iNaturalist for records of netted 
bees.  The use of iNaturalist to generate location records and plant host records is described in detail 
in Best et al. (2021). 

As in 2018, we ensured standardized and archival labels were placed on all specimens. The final 
labels were generated at Oregon State University on acid free cardstock paper and then sent to 
volunteers to place on specimens. Label information was pulled from the verified and corrected 
database and printed using BarTender software (Seagull Scientific, Bellevue, Washington) on 8.5” 
x 11” cardstock using a laser printer.  Unlike 2018, each label was associated with a unique Oregon 
Bee Atlas field number. The field number consisted of a 7-digit number. It was composed of a prefix 
year code (19) followed by a 5-digit sequential unique specimen number (e.g., specimen 1918520 is 
the record of a female Agapostemon texanus collected on Grindelia stricta by volunteer Marty Stein in 
Newport, Oregon on July 23, 2019).

Once labeled, volunteers worked to provisionally identify and sort their specimens and were 
encouraged to bring material to Oregon Bee Atlas for monthly open microscope sessions (September 
2019 – February 2020) at Oregon State University for assistance with genus-level identification.  
Volunteers were instructed to turn their collections into Oregon State University by March 2020 for 
authoritative specimen identification and voucher selection.

Specimen determinations were made by three of the authors: Lincoln Best (various taxa), Joe Engler 
(Lasioglossum), and Briana Lindh (Melissodes). Individual volunteer collections were graded (where 
applicable) by Best based on accuracy of the identification, and quality of specimen preparation. 
Every volunteer who submitted a collection received an individual evaluation grading sheet.  
Feedback was provided on misidentifications and issues with specimen preparation. Voucher 
specimens that covered both the taxonomic and geographic breadth of the sampling were accessioned 
into the Oregon State Arthropod Collection and excess material was then used to create regionally 
relevant reference collections for the volunteer teams.

Data and metadata

Once the annual data were collated into a single table, the data and metadata were checked for 
typographical errors and fields were mapped to darwinCore biodiversity data standards  
(https://dwc.tdwg.org/).

The final dataset contains the following 38 fields:

occurenceID: this is a globally unique identification number for the observational record. It is cast 
differently depending on whether the voucher specimen was retained or not.  For occurrence records 
based on specimens now housed in the collection, the occurrenceID has the prefix: http://osac.
oregonstate.edu/ followed by ‘SP/OSAC_’ followed by the 10 digit museum-issued catalog number 
for the voucher specimen,  e.g.; http://osac.oregonstate.edu/SP/OSAC_0001275241. This globally 
unique string, which is also a URL, serves as a hyperlink to access the museum specimen record.  

Observations made from specimens that were not retained as vouchers at the OSAC, were also issued 
unique ID’s as URLs with the same prefix, however the “SP/[catalogNumber]” has been replaced 



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with “OBS/OBA_[fieldNumber]”.  These will also retrieve a copy of the observation record but 
are not tied into the museum’s specimen-based inventory: e.g.; http://osac.oregonstate.edu/OBS/
OBA_1918520. 

catalogNumber: if a voucher specimen for an observation was deposited into the OSAC, it is 
provisioned with a unique catalog number, which is presented on a printed label in both arabic 
human readable digits and a datamatrix barcode.  As with the occurrenceID, the catalogNumber is 
represented in the datamatrix as a URL: http://osac.oregonstate.edu/SP/OSAC_XXXXXXXXXX, 
where the X’s correspond to a unique 10-digit number.  Observations based on specimens that were 
not accessioned into the museum (i.e., not retained) are not associated with a catalog number. 

disposition: Whereas all observational records were based on specimens examined by a taxonomist 
(Lincoln Best, Joe Engler or Briana Lindh), not all specimens were retained.  Observations for which 
a voucher specimen was not retained (e.g., accessioned into the museum) the catalogNumber is 
necessarily left blank.  The disposition field indicates if a specimen is ‘confirmedPresent’ or ‘not-
retained’ in the museum.

datasetName: The dataset name, OBA_OSAC_2019[version], is recorded in each record, in the event 
that these records are combined with other observational datasets.

basisOfRecord: all observational records in the OBA dataset are based on actual pinned specimens, 
although as noted, not all specimens were archived.

fieldNumber: This is the Oregon Bee Atlas specimen ID number. It is created when the observation is 
created and a label is issued.

bibliographicCitation: Each record in the dataset is provisioned with the full bibliographic citation for 
the dataset, enabling downstream users to cite the record explicitly.  Doing so, provides an explicit 
means to access the source of the data record and attribute proper credit to the creators of those 
records.

license: these data are released under a creative commons license that makes them useable for non-
commercial purposes with proper and appropriate attribution (eg., cited using bilbiographicCitation 
above. Details on the license can be found at: http://creativecommons.org/licenses/by-nc-sa/4.0/

institutionCode: OSAC

ownerInstitutionCode: OSAC

rightsHolder: Oregon State University

Collecting Date: The collecting date is stored in two forms, three separate parsed fields: day (1-31), 
month (1-12) and year (2019); an eventDate is included for ease of sorting by date.

locality data: locality data is stored in 6 fields: country, state, county, location, decimalLatitude, and 
decimalLongitude.  Georeferencing was provided by the collector and was either recorded in the field 
during the collecting event or determined subsequently based on maps and field notes. In all cases, 
they are recorded in decimal degrees with an accuracy of 3 decimal places (approximately +/- 100m). 



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Full georeference data is available via request to the lead author, however publicly shared records 
were rounded to the nearest integer, so as to provide visualization on GBIF mapping, while better 
ensuring that more detailed uses of the data directly attribute these records to the appropriate source 
(i.e, the dataset creators, not the data aggregator).  This information is provided in each record via the 
dataGeneralization field.

samplingProtocol: the collecting method is typically aerial net, where other means were used: eg., 
sweep net or pan trap, these were indicated.

Associated plant information: any bees that were collected in direct association with known plants 
had this information recorded in one of two ways.  If a bee or bees were collected directly from 
a plant while foraging, this information is placed into the “associatedTaxa” field, using standard 
language recommended by DarwinCore, in which the type of relationship is stated followed by a 
colon and then the plant taxon, eg., “foraging on” : “Grindelia stricta”.  In cases where a sweep net or 
pan trap or bees were netted in the vicinity of known plants (e.g., bees were not directly observed 
visiting floral resources on these plants), this is placed in fieldNotes.

Additional data and metadata associated with the plant association is available via request to the 
lead author, including voucher photographs.  This information was shared in each record via the 
informationWithheld field.

recordedBy: provides the collector’s name

Taxon: All names were crosschecked against GBIF’s species name tool prior to being uploaded. Fields 
included are: phylum, class, order, family, subfamily, tribe, genus, and species.  The full binomial with 
authority and date of publication is provided in scientificName.  

rank: lowest taxonomic rank the record is identified to
sex and caste are recorded if known.

repository: The repository is considered OSAC if voucher material was deposited in the museum.  For 
observations for which the voucher was not retained, this field is left blank.

Determination information: identification data is provided in the identifiedBy and dateIdentified 
fields. In all cases, the final 2019 dataset records were determined by Lincoln R. Best, Joe Engler or 
Briana C. Lindh.  

Findings/Results

Volunteers

A total of 128 volunteers submitted collections of bees, with approximately 60% submitting collec-
tions over 50 bees, 10% submitting collections more than 500 bees, and 5% submitting collections over 
1,000 bees submitted. 



Catalog: Oregon State Arthropod Collection   

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Spatial distribution of sampling

Wild bee specimens were collected from all 36 Oregon counties (Figure 1). Although specimen 
collection was spatially uneven across the state, 97% of specimens were collected outside of the 
Multnomah County where most of our collectors live. Moreover, 33% of specimens were collected in 
the four ecoregions (level III) east of the Cascade Mountain range (Figure 2). 

Description of the wild bee data

Volunteers collected 25,022 bees from March 02, 2019 to December 23, 2019 (Figure 3). Bees were 
predominantly collected from four bee families, Apidae, Halictidae, Megachilidae, and Andrenidae 
(Figure 4).  In total, volunteers collected bees from 45 genera, with the top five collected genera being 
Andrena (3,705 specimens), Bombus (3,517), Lasiglossum (3,259), Osmia (2,784), and Halictus (2,465) 
(Figure 4). There are 224 species listed in the dataset although many specimens from a number of 
species-rich genera (e.g., Andrena, Melissodes and Lasioglossum) were only determined to the generic 
level at the time of publication. We estimate that more than 400 species were collected by volunteers 
in 2019.  A species abundance curve of volunteer collections suggests that further sampling effort 
is required to detect all the species in state (Figure 5). Notably, volunteers identified 31% of their 

Figure 1. Heat map of 2019 volunteer sampling effort. Each dot represents a distinct sample event, which is a distinct 
collection within a specific bounded 1 ha area on a given date and time. The increasing red color of the county 
corresponds to the total number of specimens collected in the county (with totals appearing in the center of each county). 

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specimens to genera and 10% to species (Supplement 1). While volunteer determinations were largely 
correct at the genus level (94% correct), their species level determinations had notable errors (77% 
correct). 

Notable wild bee discoveries

This state-wide survey effort produced valuable occurrence records for species poorly known 
for the state, and species of conservation concern. Among the Megachilidae, new state records 
include Ashmeadiella altadenae Michener, 1936, Ashmeadiella prosopidis (Cockerell, 1897), Hoplitis 
boharti (Timberlake & Michener, 1950), Hoplitis emarginata (Griswold, 1983), and Hoplitis remotula 
(Cockerell, 1910). A. altadenae, H. boharti, and H. remotula have demonstrated fidelity to Plagiobothrys 
(Boraginaceae), while H. emarginata have only been recovered from Sedum (Crassulaceae), with a 
documented preference for species with cream-colored inflorescences. One record of the adventive 
exotic species Pseudoanthidium nanum (Mocsáry, 1881) is provided from Troutdale, which adds to a 
short but growing number of records known from the greater Portland Area.

The Oregon Bee Atlas continues to generate species occurrence data with floral associations for 
species of conservation concern including 25 records from 10 plant genera for Bombus occidentalis 
Greene, 1858, and 9 records from 4 plant genera for Bombus morrisoni Cresson, 1879. Twenty-one 
species of Bombus are documented in this dataset. Three additional records are provided for the 
squash bee, Eucera (Peponapis) pruinosa (Say, 1837), expanding its known range into the Willamette 
Valley. 

Figure 2. . Map of 2019 volunteer sampling effort by ecoregion (level III). Each dot represents a distinct sample event, 
which is a distinct collection within a specific bounded 1 ha area on a given date and time. The number of specimens 
collected per ecoregion appear in the middle of each region.



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Figure 3. Phenology plot for all bee species (y axis), sorted by median abundance times. Percentiles of overall activity of 
each bee species (50th & 90th) are shown in grey shaded regions. Date ranges for each species (minimum, first, second, 
third quartiles, and maximum) are shown only for species with >10 specimens.



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Figure 4. Number of specimens collected per taxon (y axis) by volunteers in 2018, broken down by species, genus and 
family. 



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Data for the rare Calliopsis xenus (Rozen, 1958) in Oregon is published here for the first time. This 
species is presumed endemic to the Cascade and Sierra Nevada Ranges. It has been previously 
detected by Dr. Andrew Moldenke and August Jackson in the Oregon Cascades, and both have 
produced specimens (pers. comm. to L.R.Best). Both investigators have expressed concerns that the 
populations they documented may now be extirpated, in the former case by landscaping, and the 
latter by the 2020 wildfires that swept the Oregon Cascades.

Figure 5. The number of bee specimens and unique bee species caught by all volunteers. Each volunteer’s effort is 
indicated by a dot. A linear-square root regression and 95% confidence intervals are shown by the line and shaded region.

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Catalog: Oregon State Arthropod Collection   

11

Vol 6(1) 1—13

The minute Arizona small carpenter bee, Ceratina arizonensis Cockerell, 1898, is new to Oregon. 
This species and several other new state records are known only from the vicinity of Eight Dollar 
Mountain, a significant botanical area known for high rates of endemism. Our early survey results 
support this phenomenon being shared with the pollinator fauna, with several suspected novel bee 
species awaiting further study.

Description of host plant data

A total of 16,755 bee specimens were associated with 350 unique genera of flowering plant hosts, 
within 80 families (Supplement 2). The greatest number of specimens were collected from Ericameria 
spp. (5% of plant records), followed by Phacelia spp. (4% of plant records) and Salix spp. (4% of plant 
records). Surveys across plant genera varied considerably among counties (Figure 6). The plant 
genera producing the greatest bee species richness were Phacelia, Ericameria, and Cirsium, hosting a 
total of 82, 73, and 64 unique bee species.

Figure 6. Heat map of 2019 volunteer sampling effort. Each dot represents a distinct sample event, which is a distinct 
collection within a specific bounded 1 ha area on a given date and time. The increasing green color of the county 
corresponds to the total number of plant genera that bees were caught from in the county (with totals appearing in the 
center of each county). 



Catalog: Oregon State Arthropod Collection   

12

Discussion

The second annual cycle of the Oregon Bee Atlas continues to demonstrate the potential of volunteers 
to create contemporary records of wild bees and their plant hosts on a state-wide level. To our 
knowledge, the Oregon Bee Atlas remains unique with respect to the number of collectors and the 
quality of the material they collected, but also in terms of the large extent of plant-host associations. 
Results suggest considerable return of high value data from lethal sampling that would otherwise 
not be captured by lower intensity non-lethal sampling or sentinel plant monitoring, as advocated by 
Tepedino and Portman (2021).   

These results, which are biased in taxonomic identification effort towards the genus Bombus and 
the family Megachilidae, have provided new spatio-temporal and floral data for much of the state 
fauna, and have detected new state records and suspected new species. Nearly 300 species from 47 
genera have been identified among the specimens produced from 2018 and 2019. It is estimated that 
more than 250 additional species remain among unidentified specimens from this field season. It 
is estimated that during the 2019 field season, volunteers produced specimens representing nearly 
500 species. Investing additional morphological and molecular resources to unassessed genera is 
expected to increase our state fauna to nearly 700 species among at least 55 genera.

There has recently been a call by Portman et al. (2020) for a targeted approach to bee monitoring 
that includes key ecological information such as associated host plant records.  Compared to 2018, 
volunteers continued to collect a high number of specimens that are associated with host-plant 
records. Approximately 67% of our bee occurrence records in 2019 were associated with a host plant. 
Moreover, more of the plant host records, compared to 2018, also exist in a photo vouchered format 
in iNaturalist. In 2020, we changed our protocols to ensure that all plant host records were recorded 
with a photo-voucher in iNaturalist.  The bee plant-host dataset we describe here is one of the largest 
published. Our 2019 data alone, for example, exceeds the number of bee plant-host interactions from 
a Great Plains region survey (Vilella-Arnizaut et al. 2021) by 1.7 times, with 3 times the number of 
plant genera recorded in our network.  Such datasets can be of high value to identify key forage 
plants for restoration efforts (e.g., Cane and Love, 2016; Purvis et al., 2021). 

The Oregon Bee Atlas will continue to develop and refine its training programs to prepare volunteers 
to conduct more targeted surveys associated with unique plant communities in Oregon and use 
historical records to guide volunteers. Beginning in 2020, we conducted a large overhaul in our 
training program and created the Master Melittologist program, the first master certificate program in 
the Extension service dedicated to the study of wild bees. 

Acknowledgement 

The Oregon Bee Atlas would not be possible without the hard work and dedication of its volunteers 
(see Supplement 3 for a listing of volunteers who contributed to this dataset). We are particularly 
grateful for the Oregon Bee Atlas Advisory Committee in 2019; Judi Maxwell, Missy Martin, Michael 
O’Loughlin, Jerry Paul, Pete and Gretchen Peterson, Nicole Sanchez, and Bonnie Shoffner. We are 
grateful to the Foundation for Food and Agriculture Research Pollinator Health Fund and Oregon 
Department of Agriculture for supporting the Oregon Bee Atlas. 
 

Vol 6(1) 1—13



Catalog: Oregon State Arthropod Collection   Vol 6(1) 1—13

13

References

Best, L.R., C. Feurborn, J. Holt, S. Kincaid, C.J. Marshall, A. Melathopoulos and S. Robinson. 2021. 
Oregon Bee Atlas: native bee findings from 2018. Catalog: Oregon State Arthropod 
Collection. DOI: http://dx.doi.org/10.5399/osu/cat_osac.5.1.4647.

Cane, J.H. and B. Love. 2016. Floral guilds of bees in sagebrush steppe: comparing bee usage of 
wildflowers available for postfire restoration. Natural Areas Journal, 36(4), pp.377-391.

Portman, Z.M., B. Bruninga-Socolar and D.P. Cariveau. 2020. The state of bee monitoring in the 
United States: A call to refocus away from bowl traps and towards more effective 
methods. Annals of the Entomological Society of America 113(5), pp. 337–342.

Purvis, E.E., L.R. Best, and P. Galpern. 2021. Identifying key forage plants to support wild bee 
diversity and a species at risk in the Prairie Pothole Region. Insect Conservation and 
Diversity, 14(6), pp. 851-861.

Tepedino, V.J. and Z.M. Portman. 2021. Intensive monitoring for bees in North America: 
indispensable or improvident? Insect Conservation and Diversity, 14(5), pp. 535-542.

Vilella-Arnizaut, I.B., H. Nottebrock, C.B. and Fenster. 2021. Quantifying habitat and landscape effects 
on composition and structure of plant-pollinator networks in the US Northern Great 
Plains. BioRxiv. https://doi.org/10.1101/2021.02.12.431025

Westphal, C., R. Bommarco, G. Carré, E. Lamborn, N. Morison, T. Petanidou, S.G. Potts, S.P. Roberts, 
H. Szentgyörgyi, T. Tscheulin and B.E. Vaissière. 2008. Measuring bee diversity in 
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