Is Hylaeus sparsus a pollen specialist?

[Droege, Sam]

Is Hylaeus sparsus a pollen specialist?

Jarrod Fowler (copied) has created lists of bees that are pollen specialists

East: Pollen Specialist Bees of the Eastern United States

Central: Pollen Specialist Bees of the Central United States

West: Pollen Specialist Bees of the Western United States

and even cuckoo bees who target specialist bees: Pollen Specialist Cuckoo Bees of the United States

"Specialist" needs a definition because each species has its predilections. So, if you primarily gather pollen from plants in a single family or below you can be defined as a "specialist." 

Information for uncommon species can prevent a species from getting listed and that might be true for some Hylaeus.

In general, Hylaeus are out for most of the growing months which makes them unlikely to fit a definition of specialist.  But. There is one Hylaeus that shows up on Jarrod's list ... H. basalis a northern specialist on potentilla.

Recently, I am wondering if H. sparsus should be on that list as an Apiaciae specialist as was pointed out by Sellers and McCarthy a while back.

Sellers, E. and McCarthy, D., 2015. Distribution and floral hosts of Anthophorula micheneri (Timberlake, 1947) and Hylaeus sparsus (Cresson, 1869),(Insecta: Hymenoptera: Apoidea: Anthophila), with new state records in Giles and Loudoun counties, Virginia, eastern USA. Check List, 11(3), pp.1-11.

Our lab has collected relatively few of this species, in fact just 12 out of several hundred thousand specimens.  Those collection have been in several locations and included netting, malaise, canopy traps but no bowls (Hylaeus are generally not that attracted to bowls on the ground).

Recently I collected bees off of Golden Alexanders (Zizia aurea) planted at my home and caught > 10 H. sparsus males and females.  I went to work and similarly collected another 10+ on the same plant.  I had not previously collected off these plants and they don't occur naturally nearby.  Other species in the carrot family do occur nearby but in the spring they tend to be species that are small, scattered, and overlooked (Sweet Cicely Ozmorhiza claytonii is a good example, common but not showy).  Certainly, summer Apiaceae support large numbers of Hylaeus of multiple species but we are talking spring here.

So, I am wondering what other folks have found H. sparsus using, and whether there has been much collecting on spring Apiaceae at all.

Additionally, it is also interesting to see that Apiaceae has no known bee "specialists" which throws some shade on that group supporting specialists or, are they simply the most convenient of plants for a little short tongued bee?

On the other hand, why only come out in spring if there are Apiaceae a plenty the rest of the year that your cousins are using?

While we are at it we might look at the only other spring Hylaeus that I am aware of in the East. ... H. georgicus, super rare.

On top of that there is the similar in appearance H. floridanus which has what appears to be a spring and a fall set of observations ... or, are there two species?

I look forward to your observations of

1. H. sparsus
2. Bees on spring Apiaceae
3. H. georgicus
4. H. floridanus

Note, go ahead and reply to the whole list...a topic of general interest.

Thanks

sam

Keep your Property Half Wild

Cell: 301 433 5390

Alternative email: droe...@gmail.com

 

[Michael Arduser]

Sam, here are the (only) plants we've collected female Hy. sparsus from in Missouri (1985-2025):

Taenidia integerrima

Sanicula greggaria

Osmorhiza longistylis

Zizia aurea, Z. aptera

All are Apiaceae; the majority of collections are from Zizia.

Also, Andrena ziziae and An. vernalis are specialists on (primarily) Zizia.

Mike

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[Davis, Jason M. (DNREC)]

Hi

 

Hope this helps!

 

All specimens collected in DE

collected a male Hylaeus sparsus from Zizia aurea along a river floodplain and another male in a bog either on either Salix nigra or an unknown white flower that Ill need to track down the picture for it for ID

collected a female Hylaeus floridanus in bowls adjacent to an interdunal swale, need to track down what was flowering at the time

collected a male Hylaeus floridanus on one of these plants (solidago, ny ironweed, verbena, common milkweed)

collected 2 male Hylaeus georgicus from Salix nigra

collected 1 male Hylaeus sparsus from Salix nigra

 

J Davis

DE Division of Fish and Wildlife

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[Nash Turley]

Hi Sam! 

One of our volunteers in the Pennsylvania Bee Monitoring Program caught 8 Hylaeus sparsus in 2023 in Chester Co. PA, 6 were netted off Zizia, and 2 off Osmorhiza longistylis. 

Here's a table of species that we've caught off Zizia, we probably have other spring Apiaceae host records, but I'll need to do some clearing up and filtering of our host record column, which I could so at some point :) 

species	count
Andrena cressonii	13
Hylaeus sparsus	6
Andrena nasonii	5
Andrena personata	4
Augochlora pura	4
Augochloropsis metallica	4
Ceratina calcarata	4
Colletes inaequalis	4
Nomada pygmaea group	4
Andrena alleghaniensis	3
Hylaeus fedorica	3
Hylaeus mesillae	3
Andrena illini	2
Ceratina strenua	2
Lasioglossum ephialtum	2
Nomada luteoloides	2
Andrena alleghaniensis/atlantica	1
Andrena crataegi	1
Andrena imitatrix/morrisonella	1
Augochlorella aurata	1
Bombus impatiens	1
Hylaeus modestus	1
Lasioglossum cressonii	1
Nomada cressonii group	1
Nomada denticulata	1
Nomada imbricata	1
Xylocopa virginica	1

Nash 

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[Molly Jacobson]

There's Andrena ziziae and Andrena vernalis which are presumably Zizia specialists. We also get Nomada mr-1, that mysterious A. ziziae parasite, alongside it on the Zizia here in New York.

-Molly Jacobson

------------------

Molly Jacobson

M.S. Conservation Biology

Native Pollinator Ecologist

SUNY-ESF Restoration Science Center

Illick 255 | mmja...@esf.edu

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Subject: Re: [Beemonitoring] Is Hylaeus sparsus a pollen specialist?

 

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[James Cane]

Sam- John Hilty's digitization of Robertson's records plus a few b John Lovell and another pair of investigators lends support to your contention that Hylaeus sparsus has a fondness for Apiaceae. 

https://www.illinoiswildflowers.info/flower_insects/insects/bees/hylaeus_sparsa.htm

In my studies of bees of Lomatium across the Intermountain West, I expected that some of the dozens of Andrena species would be pollen specialists, but only two have that possibility. Seems odd, for Lomatium bloom is as reliable as that of willows...we just had a 24F freeze during bloom, which clobbered all the flowers and fruits of valley trees, even open flowers of hardy native balsamroots, but lomatiums were inscathed. Individual L. dissectum live for at least 40 years too, judging by my transplants of what were already massive tap roots. Ah well, mysteries keep us interested, eh?

jim

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James H. Cane

Native bee and pollination ecologist

Emeritus USDA-ARS Bee Lab, Logan, Utah

owner -  WildBeecology

https://www.researchgate.net/profile/Jim-Cane

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"Knowledge and comprehension are the joy and justification of humanity"
 Alexander von Humboldt

[Douglas Yanega]

Our holdings are primarily (but not exclusively) western, and most of
the bees have host records.

Scanning the database, which is by no means exhaustive, I see several
species names that appear three or more times when looking at all 282
Apiaceae records (excluding Andrena ziziae):

Andrena: angustitarsata, atypica, candida, and chlorogaster.

Hylaeus: affinis, illinoisensis, m. mesillae, m. cressonii, modestus
citrinifrons, nevadensis, polifolli, and verticalis.

There are other bees on the list, but they're either singletons, or
obvious generalists (like Bombus).

We have no identified specimens of Hylaeus sparsus, georgicus, or
floridanus.

Peace,

--
Doug Yanega Dept. of Entomology Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314 phone: 951-827-4315
FaceBook: Doug Yanega (disclaimer: opinions are mine, not UCR's)
https://faculty.ucr.edu/~heraty/yanega.html
"There are some enterprises in which a careful disorderliness
is the true method" - Herman Melville, Moby Dick, Chap. 82

[Lusha Marguerite Tronstad]

We worked on a rare clover in central Wyoming and found that Andrena solo was the only visitors during the early blooming period. Our paper is attached.

Lusha

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[Bill Stitt]

Sam

we, Amy Schnebelin and myself caught H sparsus last spring doing a timed monitoring on Phacelia pursi but there was Osmorhiza claytonii mixed in. This past Saturday we collected both male and female on Zizia aurea and Osmorhiza longistylus that where growing in the same general area in Cleveland Metroparks. I also collected some from Osmorhiza in Cuyahoga Valley National park on Saturday too but only males. 

As a side note I also collected a male Hylaeus mesillae Saturday too. 

Bill Stitt

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[Michael Veit]

Hi Sam,

I've got a few records to share for the Hylaues spp. you are interested in.

H. sparsus females - 8 specimens/4 collecting events on Thaspium; 2 specimens/2 collecting events on Zizia

H. sparsus males - 5 specimens/3 collecting events on Zizia; 1 specimen on Thaspium; 1 specimen on Lupinus perennis; 1 specimen on Cerastium; 1 specimen on Heuchera

H. georgica males only - 2 specimens/1 collecting event on Packera

Michael Veit

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[Parys, Katherine - REE-ARS]

Hi folks- 

I've got a few records here of the other Hylaeus, but we haven't caught sparsus.... 

H. floridanus - 1 female from MS in a Malaise trap and 2 males (one each from AR and MS) one with no host plant recorded and one in a Warner trap. 

H. georgica - 1 female from LA in a Malaise trap and 2 males from here in MS both caught on Photinia serratifolia (Rosaceae). 

And we haven't done a ton of collecting on Apiaceae in general, but what I've got is below:

hostplant	sciname	CountOfsciname
Anethum graveolens	Lasioglossum (Dialictus) coactus (Cresson, 1872)	1
Anethum graveolens	Lasioglossum (Dialictus) hitchensi Gibbs	1
Anethum graveolens	Lasioglossum (Dialictus) imitatum	1
Anethum graveolens	Lasioglossum (Dialictus) spp. (tegulare sp. grp.)	1
Chaerophyllum tainturieri	Andrena spp.	1
Chaerophyllum tainturieri	Megachile (Litomegachile) mendica Cresson	1
Chaerophyllum tainturieri	Panurginus polytrichus Cockerell	4
Daucus carota	Andrena (Micrandrena) personata Robertson	1
Daucus carota	Andrena (Opandrena) cressonii cressonii Robertson	3
Daucus carota	Ceratina (Zadontomerus) shinnersi Daly	1
Daucus carota	Halictus (Odontalictus) ligatus/poeyi	3
Daucus carota	Hylaeus spp.	3
Daucus carota	Lasioglossum (Dialictus) imitatum	1
Daucus carota	Sphecodes spp.	1
Daucus carota	Xylocopa (Xylocopoides) virginica (L.)	1
Pastinaca sativa	Bombus (Cullumanobombus) griseocollis (DeGeer)	1

Katherine

-- 

Dr. Katherine A. Parys

USDA Agricultural Research Service

Southern Pollinator Health Center

Pollinator Health in Southern Crop Ecosystems Research Unit

141 Experiment Station Rd./ PO Box 346

Stoneville, MS 38776

katheri...@usda.gov

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[Virginia L Scott]

 

I have a MALE Hylaeus sparsus I collected from Ranunculus acris on June 20 1985 in Dickinson County (T43N R30W Sec 19) Michigan (in the UP).  I collected a lot of Hylaeus up there, many from umbels, but this is the only H. sparsus I ever collected.

 

Va

Ms. Virginia Scott (she/her)

Entomology – Senior Collections Manager

University of Colorado Museum of Natural History

265 UCB – MCOL

Boulder, CO 80309-0265

http://www.colorado.edu/cumuseum/research-collections/entomology

 

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[Lorraine Clarke]

In my study on bees in Bowie Pollinator gardens, I found a total of 17 Hylaeus bees (H. affinis, H. leptocephalus, H. mesillae, and H. modestus). Of those, 2 H. mesillae were found on Boltonia, 2 H. mesillae were found on Erigeron, and the rest of the Hylaeus were found ONLY on Solidago and Symphotrichum flowers (genera we had specifically marked as attractive to specialist bees). I marked this when I found it, as we were looking at other specialist bees (Melissodes and Lassioglossum), but Hylaeus also seemed to specialize. 

Here are the actual counts:

Hylaeus affinis: Solidago odora (1)

Hylaeus leptocephalus: Symphotrichum oblongifolium (2)

Hylaeus mesillae: Boltonia asteroides (2), Erigeron strigosa (2), Solidago odora (11), Solidago rugosa (2), Solidago sempervirens (2), Symphotrichum oblongifolium (1)

Hylaeus modestus: Solidago odora (1), Symphotrichum oblongifolium (1)

Definitely ONLY asters for mine. 

[David C]

We have conducted a study in SE Michigan, to construct pollinator networks for spring flowers. This was a citizen science project, not intended to address a particular hypothesis, but to capture the overall picture. Which species appear to be most important, in numbers and host range? On what plants would we find specialists, or rare taxa? How do focal plants fare at disparate sites? Etc. Some of the data near the top of this page.

One of the surprising findings: trees. In a small forest preserve, we were interested in ephemerals. But we also sampled woody plants in the forest and in surrounding open space. We didn’t quantify pollinator abundance on plants we sampled, but It became clear that the floral resources represented by redbud, apple/pear, cherry, willow, and dogwood likely exceeded what woodland forbs offered. An extreme case: working in a 5 acre woodlot, an hour’s observation of trout llily, spring beauty, toothwort might net a dozen bees. Walking out of the woodlot, a stop at a mature apple tree might net a dozen bees with each sweep of the net. 

Question 1: Does this observation comport with what others have observed? If so, any evaluation of pollinators on valued wildflowers should account for what is happening in trees. I can suggest at least 3 hypotheses: 1) Trees support reproduction of many bees - Ceratina, Andrena, Colletes especially - and these “overflow” to the benefit of spring forbs; 2) Trees out-compete forbs, drawing bees away; 3) Trees are serviced by a different set of pollinating species, and so have little effect. My sense is that each of these options is at play to some extent.

Related question 2: Does it make sense to promote tree species that are especially beneficial to pollinators? There is enormous public interest in establishing native plant gardens for pollinators. But if the goal was to support pollinators in general, trees might be a more effective investment. Of course there are many complicating variables, like: which bees? But in any case we are considering offering advice to local conservationists, to encourage including e.g., redbud or willow for the benefit of pollinators.

Thanks for your thoughts!

--------------------------------------

David Cappaert

Quamash EcoResearch

[James Cane]

Hi Dave- your experience mirrors mine over the decades both here in northern Utah as well as in Alabama. Shrubs belong in your list too, thinking of Ribes, Berberis, bitterbrush, and Rhus here...most of our willows are shrubby too, and they can shimmer with wild bees. Maples too, as Suzanne Batra published decades ago. I rarely saw a bee at flowering dogwoods in Alabama, but I recollect that Peter Bernhardt and cohort report more in Missouri. I used to dismiss chokecherry until I found some plants thronged with Andrena at a campground over in the remote Ruby Mtns of Nevada. The challenge is convincing homeowners and personnel overseeing campuses, parks and buildings to plant these choices. I've been told, for instance, that redbuds are "messy" by a park manager who merrily planted honey locusts (with their noisy masses of useless big pods). By learning all this first-hand, you and others in your locale gain credibility and vivid stories when giving local talks or advising folks or speaking with journalists, which will add to the chorus for good choices to plant for wild bees and ultimately get more in the ground.

yerz, jim   

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[Douglas Yanega]

On 6/16/26 8:10 AM, 'David C' via beemonitoring wrote:

Question 1: Does this observation comport with what others have observed? If so, any evaluation of pollinators on valued wildflowers should account for what is happening in trees. I can suggest at least 3 hypotheses: 1) Trees support reproduction of many bees - Ceratina, Andrena, Colletes especially - and these “overflow” to the benefit of spring forbs; 2) Trees out-compete forbs, drawing bees away; 3) Trees are serviced by a different set of pollinating species, and so have little effect. My sense is that each of these options is at play to some extent.

I spent 6 years observing a population of Halictus rubicundus in New York City (Queens). I routinely sampled their pollen loads. I also sampled pollen from plants in the area, including trees. As far as I could tell (with my ID skills limited to finding a visual match between a bee sample and a reference sample), most of the pollen they were gathering was from flowering trees, such as Prunus, Pyrus, Malus, and possibly Acer. They also visited things like Trifolium, Taraxacum, Hypochaeris, Coreopsis, etc. Individual bees seemed to have preferences, but could switch from trip to trip. If anyone is really, really good with pollen ID, I still have all the samples available. Could make for a nice little publication.

I will also vouch for redbud and willow being excellent plants supporting many native bee taxa, and out west here, mesquite, Chilopsis, and palo verde are amazing bee resources.

Related question 2: Does it make sense to promote tree species that are especially beneficial to pollinators? There is enormous public interest in establishing native plant gardens for pollinators. But if the goal was to support pollinators in general, trees might be a more effective investment. Of course there are many complicating variables, like: which bees? But in any case we are considering offering advice to local conservationists, to encourage including e.g., redbud or willow for the benefit of pollinators.

Makes sense to me, so long as the trees are native, and not some horrible thing like Bradford Pear. ;-)

[Russel Barsh]

David --

This is definitely what we see here in the Salish Sea region, where woody species attract clouds of wild bees (and honeybees, too) when they bloom. Nootka Rose and Snowberry are favored by Bombus, for example; many solitary bees swarm in Oceanspray (Holodiscus discolor) which often has its own community of nearby ground-nesters such as Colletes. 

Our lab operates a research farm, and we have devoted much of our last five years to helping restore 150-year old apple orchards in the islands to production. One thing this has taught us, is that old orchards assembled have their own pollinator communities, which are disrupted if the old trees are cut down and replaced with young ones. (They also have distinctive avian and mammal residents, including rare bats.) Like old forests functionally. We are trying to persuade landowners to leave old deciduous woodlands AND old orchards undisturbed -- for pollinators.

Russel.
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Director, KWIAHT

PO Box 415, Lopez Island WA 98261

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[Sam O'Dell]

David,

Q1: Yes... I have seen many a cloud of bees surrounding apple, Prunus (various species in various places), and other trees. On the other hand, I have only recently worked with flowering tree species in areas that are largely (or even partly) forest. The number of individual flowers on these trees and shrubs can dwarf what most herbaceous plants can offer....

Q2: There is no doubt that trees, including but not limited to those you mentioned, are important in supporting pollinators. Promote those that you think match the other needs of the space or garden. I like redbud and in OK you can reliably find bees visiting these trees; the visitors aren't as diverse as they are on other trees/shrubs like Prunus. One potential drawback of including trees is that many species are early flowering and not as likely to support as many species as say certain shrubs or herbaceous plants that occur later in the season. 

I enjoyed checking out the website, and from your network graph it seems like a few of the plants may be subsidizing the activity at other plants... but this doesn't appear to be limited to trees, as Geranium and spring beauty appear to support quite a few species as well. This is a common pattern. A practical problem might be trying to "sell" trees in an area that is predominantly forest, where cool wildflowers are sort of the known and preferred medium of pollinator plantings. These trees and shrubs will likely add resources when few other things are going, supporting spring emerging bees and adding some color to those landscapes.

Best,

Sam

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[Elise McDonald]

Hi David and Friends, 

Thanks for raising this topic! I am based in Georgia, and my research interests are really focused on bees among trees. Trees are very important for bees, and our research here in the southeast has found that certain species are highly associated with forested landscapes, even in more urban areas (the southeast is heavily forested, even the cities). There are some species we catch in abundance in forests that are rare in open area sampling. Here's my two cents :)

Q1) You're right on the money! Trees seem to support a lot of different bee species. It seems possible that during the time when certain trees are in bloom, those trees might be more attractive to bees than some other flowers. If they are, it's probably because they are adapted to be highly fragrant/desirable to draw the attention of the bees up to where the blooms are since most bees are generally low-flying, and don't hang out in the canopy much. Also, especially in the case of redbuds, early spring blooming trees might be some of the first nectar sources available. If there is a bit of an outcompeting factor, I suspect it's negligible. 

Trees (individual trees as well as forests) are extremely overlooked as important bee forage and habitat. Though sampling reveals bees don't spend as much time in the canopy, they are readily attracted to fragrant blooms up there. Even oak trees, which have small and unimpressive inflorescences, will be loaded with bees (especially Lasioglossum and other littles) when in bloom. Same thing with yellow poplar, black cherry, other fruit trees, and some of the others you mentioned. Honeybees also love these canopy flowers, as indicated by specialty honey such as sourwood and tupelo, which is available when these trees are in bloom, and are endemic and highly sought after in our region. Besides foraging, bees nest in cavities left behind by boring insects like bark beetles, utilize their resin, nest under their roots in abandoned rodent holes, etc. Bees might exist in higher numbers in open areas, but they are abundant and diverse in forests as well, and we have evidence that there might be a good many forest specialists out there. These flowering trees are also great forage in places where flowering understory veg is missing due to land management in urban spaces, or high canopy density in forests that have not been managed to have open understories. Forests might also provide refuge from some of the stresses in more open areas, such as competition with honeybees. 

Q2) Yes! Promoting the planting of native, site adapted, and if possible, flowering trees, is fantastic and definitely worth it. Even non-flowering trees are useful for nest sites and resin resources, though, so I don't count those totally out if a landowner/manager prefers them or if the site calls for it. 

It is so interesting that you bring this up - I taught a webinar on how bees utilize trees literally an hour ago! 

Cheers,

Elise McDonald

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[Kit Prendergast]

Hi Beeple,

My experience in southwest Western Australia has definitely found that trees are major important resources.

For example, my research on Corymbia calophylla found that 81 native bee species visit this tree; furthermore it blooms when the wildflower season here in SWWA has tapered off:
Prendergast, K. S., & Willers, N. (2024). Corymbia calophylla (Marri) (K. D. Hill & L. A. S. Johnson) (Myrtaceae) is a major resource for native bees in the southwest western Australian biodiversity hotspot. Pacific Conservation Biology, 30(6), PC24054. https://doi.org/https://doi.org/10.1071/PC24054 

You can also see here that the top visited plants are predominantly shrub/trees:
Prendergast, K. S. (2023). Native flora receive more visits than exotics from bees, especially native bees, in an urbanised biodiversity hotspot. Pacific Conservation Biology, 30, PC22033-. https://doi.org/https://doi.org/10.1071/PC22033

I suspect in a crop context eucalypts probably compete with crop pollination - why go to canola when you can go to a eucalypt? But almost no native bees will visit canola anyway in Australia (based on my postdoc research).

There's increasing calls in urban areas to increase canopy cover, but unforatuntely these initiatives are done without consideration of the biodiversity value of the trees being planted. A major missed opportunity to help both boost urban native bee biodiversity and improve canopy cover.

Best,

Kit 

To view this discussion visit https://groups.google.com/d/msgid/beemonitoring/CALP0pH%3DAXuxzaa91GTpmU-uwTLYZBaetu7d-vtnJyN6NrG%3DO_g%40mail.gmail.com.

--

Dr Kit Prendergast

Native bee scientist, conservation ecologist and science communicator

University of Southern QLD Postdoctoral Researcher (Pollination Ecology)

Wild Bee Specialist Group Communications Lead

Adjunct Curtin University and Univerisity of Western Australia

Forrest Scholar Alumni

Find native bee resources and more on my Patreon The Bee Babette: https://www.patreon.com/c/TheBeeBabette

ORCiD: https://orcid.org/0000-0002-1164-6099 

Research: https://www.researchgate.net/profile/Kit-Prendergast/research

YouTube channel The Bee Babette: https://www.youtube.com/c/TheBeeBabette 

'Creating a Haven for Native Bees': https://www.facebook.com/CreatingaHavenforNativeBeesBook/

Wild Bee artwork: https://www.redbubble.com/people/BeeBabette/explore?asc=u&page=1&sortOrder=recent

Insta: @bee.babette_performer:

https://www.instagram.com/bee.babette_performer/?hl=en

[Graham Pyke]

Just to add my own experience with bees and trees….

 

Many years ago, in the deserts of Arizona, I observed and collected many bees on trees, including several species in the genus Perdita, that specialised on visiting flowers of Mesquite trees (Prosopis spp). Somewhat later, I donated my bee collection, which also included many Bombus from UT, CO & AZ,  with over 8,000 specimens, to the Macleay Museum at USyd. And there they sit, unappreciated, with much potentially useful information associated with each specimen. Sigh!

 

Does that make me a bono fide bee person?

 

Graham

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[John Mola]

Hi folks,

There is a lot of recent literature on this topic. A good chunk of it is also summarized in a Society of American Foresters webinar series from a couple years back. I could not find the main landing page for the series, but typing in "pollinator" as a keyword on SAF's "eforester" website yields all the talks in a list: https://learn.eforester.org/search-full-site#form_type=entity-search-form&entity_types[]=product&entity_types[]=file&keywords=pollinator&product-skip=0&product-take=10&file-skip=0&file-take=10&feed-skip=0&feed-take=10&podcast-skip=0&podcast-take=10&union-skip=0&union-take=10&type_reload=

I'd recommend checking out Michael Ulyshen and Kass Urban-Mead's work on the topic. They have a nice review here: https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12947 which then cites dozens of relevant papers. Kass, in particular, has done the actual climbing to get into trees and make observations. Fun stuff. 

In my own work, though "only" with bumble bees, we recognized a pattern of studies being about [something else] and then concluding that forest cover (and often forest edge) ended up being a major explanatory factor in results. e.g., for nest-searching queens, for overwintering locations, or for (directly) unexplained reasons that are likely a combination of early-season resources, climate microrefugia, complementary phenologies, etc etc. 

I only have my limited experience in Denver, Colorado, USA - but the city of Denver is explicitly considering pollinator forage in their selection of urban canopy trees to replace those lost by Emerald Ash Borer (something like ~15% of Colorado's urban canopy is ash (Fraxinus), currently). 

See ya,

John

To view this discussion visit https://groups.google.com/d/msgid/beemonitoring/SY2PPF45FBEF9A49AA39143E3BAFAC4AA8FBFE42%40SY2PPF45FBEF9A4.ausprd01.prod.outlook.com.

--

John M. Mola

molalab.org

Please note: If your message is about science, bees, or official CSU business, please direct your message to john...@colostate.edu and I will update my contacts for you there -- thank you!

[James Cane]

Thinking of planted redbuds, when I arrived at the University of Kansas in the late 70s, there was a long colonnade of them planed on both sides of a campus sidewalk. When they bloomed, it was stunning (take note landscape architects in your imaginative renderings of new buildings). I wish that I had a photo of it. I might add, of course, that leaf-cutting Megachile are fond of their foliage for lining their nest cells. How much more can one native tree offer to a bee? Of, and if on a campus, their bloom might coincide with graduation, putting alumni in a cheerful mood to donate to the university.

jim

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[Droege, Sam]

All

I have been enjoying the conversation on bees and trees.  

I will add emphasis to a few points when thinking about what to plant at a site or city scale.

First, most of the tree discussed are supporting generalist oligolectic bee species.  In any area many of the bees of conservation concern will be specialists not generalists.  Thus think about trying to emphasize woody plants that support specialist species.  Lists of what we know to be likely specialist species can be found using Jarrod Fowler's works for North America north of Mexico.

East Pollen Specialist Bees of the Eastern United States

Central Pollen Specialist Bees of the Central United States

West Pollen Specialist Bees of the Western United States

These plants will also support most of the generalists as well.  It's not an either-or situation, plenty of room for both.  

Another important factor to think about is timing.  Often trees and shrubs that focus on generalists have relatively short bloom period (<2 weeks) while any particular bee species will be out for much longer than that.  Thus, plotting out the patterns of bloom over time for candidate tree species will be helpful to provide provisions throughout the spring/early summer.  Specialist woody plants tend to have longer bloom periods to more fully support (presumably) their specialist species and this adds another reason to include them in your line up.  Late blooming species are often overlooked so you might want to tie up your woody plant strategy by adding those (e.g., in the east, winged sumac, chinquapin, sourwood, persimmon, lyonia, etc.) 

Sam

WHEN I AM AMONG THE TREES

When I am among the trees,

especially the willows and the honey locust,

equally the beech, the oaks and the pines,

they give off such hints of gladness.

I would almost say that they save me, and daily.

I am so distant from the hope of myself,

in which I have goodness, and discernment,

and never hurry through the world

but walk slowly, and bow often.

Around me the trees stir in their leaves

and call out, “Stay awhile.”

The light flows from their branches.

And they call again, “It’s simple,” they say,

“and you too have come

into the world to do this, to go easy, to be filled

with light, and to shine.”

      - Mary Oliver

---

From: beemon...@googlegroups.com <beemon...@googlegroups.com> on behalf of John Mola <john...@gmail.com>
Sent: Wednesday, June 17, 2026 11:37 AM
To: graha...@mq.edu.au <graha...@mq.edu.au>
Cc: kitprendergast21 <kitprend...@gmail.com>; elise.mc...@gmail.com <elise.mc...@gmail.com>; capp...@comcast.net <capp...@comcast.net>; 'Google Groups' via beemonitoring <beemon...@googlegroups.com>; Carmen Dasilva <carmen....@mq.edu.au>; Katja Hogendoorn <katja.ho...@adelaide.edu.au>; David Field <david...@mq.edu.au>; jbdorey <jbd...@me.com>; Bill Bateman <Bill.B...@curtin.edu.au>; Amy-Marie Gilpin <a.gi...@westernsydney.edu.au>; Encinas-Viso, Francisco (NCMI, Black Mountain) <Francisco.E...@csiro.au>; Scarlett Howard <Scarlet...@monash.edu>
Subject: [EXTERNAL] Re: [Beemonitoring] Floral resources in fragmented habitats

 

 

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[Flatbush Gardener]

Jarrod Fowler has another table I've found useful in plant selection: Host Plants for Pollen Specialist Bees of the Eastern United States. It's organized by flowering plant family. Most of the 55 woody species are shrubs, but there are a few trees, as well.

The chart is mine, from their data.

Genus species	Common name	Habit
Ilex glabra	Inkberry	Shrub
Ilex montana	Mountain holly	Shrub
Ilex mucronata	Catberry	Shrub
Ilex opaca	American holly	Tree
Ilex verticillata	Common winterberry	Shrub
Baccharis halimifolia	Eastern baccharis	Shrub
Cornus (Swida) alternifolia	Alternateleaf dogwood	Shrub
Cornus (Swida) amomum	Silky dogwood	Shrub
Cornus (Swida) racemosa	Gray dogwood	Shrub
Cornus (Swida) rugosa	Roundleaf dogwood	Shrub
Cornus (Swida) sericea	Redosier dogwood	Shrub
Arctostaphylos uva-ursi	Kinnikinnick	Shrub
Epigaea repens	Trailing arbutus	Shrub
Kalmia angustifolia	Sheep laurel	Shrub
Kalmia latifolia	Mountain laurel	Shrub
Rhododendron arborescens	Smooth azalea	Shrub
Rhododendron atlanticum	Dwarf azalea	Shrub
Rhododendron calendulaceum	Flame azalea	Shrub
Rhododendron canadense	Rhodora	Shrub
Rhododendron groenlandicum	Bog Labrador tea	Shrub
Rhododendron maximum	Great laurel	Shrub
Rhododendron periclymenoides	Pink azalea	Shrub
Rhododendron prinophyllum	Early azalea	Shrub
Rhododendron viscosum	Swamp azalea	Shrub
Andromeda polifolia	Bog rosemary	Shrub
Chamaedaphne calyculata	Leatherleaf	Shrub
Eubotrys racemosus	Swamp doghobble	Shrub
Gaultheria procumbens	Eastern teaberry	Shrub
Lyonia ligustrina	Maleberry	Shrub
Gaylussacia baccata	Black huckleberry	Shrub
Vaccinium angustifolium	Lowbush blueberry	Shrub
Vaccinium corymbosum	Highbush blueberry	Shrub
Vaccinium fuscatum	Black highbush blueberry	Shrub
Vaccinium macrocarpon	Cranberry	Shrub
Vaccinium pallidum	Blue Ridge blueberry	Shrub
Vaccinium stamineum	Deerberry	Shrub
Cercis canadensis	Eastern redbud	Tree
Ceanothus americanus	New Jersey tea	Shrub
Dasiphora fruticosa	Shrubby cinquefoil	Shrub
Salix amygdaloides	Peachleaf willow	Shrub
Salix bebbiana	Bebb willow	Shrub
Salix candida	Sageleaf willow	Shrub
Salix caroliniana	Coastal plain willow	Tree
Salix discolor	Pussy willow	Shrub
Salix eriocephala	Missouri River willow	Shrub
Salix humilis	Prairie willow	Shrub
Salix interior	Sandbar willow	Shrub
Salix lucida	Shining willow	Shrub
Salix myricoides	Bayberry willow	Shrub
Salix nigra	Black willow	Tree
Salix pellita	Satiny willow	Shrub
Salix petiolaris	Meadow willow	Shrub
Salix pyrifolia	Balsam willow	Shrub
Salix sericea	Silky willow	Shrub
Salix serissima	Autumn willow	Shrub

Yours in Nature,

Xris

-----

Chris Kreussling (Flatbush Gardener)

Certified Interpretive Guide, NY Master Naturalist

Web Site/Blog - iNaturalist (Observations) - Flickr (Photos) - Vimeo (Videos) 

  - Social - Signal 

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[David C]

Thanks to all for great information and ideas, which will help us to create and promote a bee forage tree list (with redbud for sure!).  I appreciated John’s observation about studies being about [something else] and then concluding that forest cover (and often forest edge) ended up being a major explanatory factor in results. Precisely my experience. 

--------------------------------------

David Cappaert
734.635.7750

Biological Observations 2026

[Jonathan Mawdsley]

An attractive resource on trees and bees, from our friends at Pollinator Partnership, with citations to various scientific publications further down the web page: 

https://www.pollinator.org/shop/poster-2016

Also my own work with collaborators in South Africa:

https://www.tandfonline.com/doi/abs/10.1080/00222933.2016.1216194

Best regards,

Jonathan Mawdsley

jonathan...@hotmail.com

(202) 997-6628

"A bee amongst the flowers in spring, is one of the most cheerful objects that can be looked upon.  Its life appears to be all enjoyment; so busy, and so pleased." - William Paley, Natural Theology, 1802.

---

From: 'Droege, Sam' via beemonitoring <beemon...@googlegroups.com>

Sent: Friday, June 19, 2026 9:54 AM
To: graha...@mq.edu.au <graha...@mq.edu.au>; john...@gmail.com <john...@gmail.com>

Cc: kitprendergast21 <kitprend...@gmail.com>; elise.mc...@gmail.com <elise.mc...@gmail.com>; capp...@comcast.net <capp...@comcast.net>; 'Google Groups' via beemonitoring <beemon...@googlegroups.com>; Carmen Dasilva <carmen....@mq.edu.au>; Katja Hogendoorn <katja.ho...@adelaide.edu.au>; David Field <david...@mq.edu.au>; jbdorey <jbd...@me.com>; Bill Bateman <Bill.B...@curtin.edu.au>; Amy-Marie Gilpin <a.gi...@westernsydney.edu.au>; Encinas-Viso, Francisco (NCMI, Black Mountain) <Francisco.E...@csiro.au>; Scarlett Howard <Scarlet...@monash.edu>

Subject: Re: [EXTERNAL] Re: [Beemonitoring] Floral resources in fragmented habitats

 

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[LR Best]

The Melittoflora contains an enormous amount of interaction data between bee species and trees, and woody shrubs.

To view this discussion visit https://groups.google.com/d/msgid/beemonitoring/BN7PR02MB5345E6C602A1006D2676F8D8E4E02%40BN7PR02MB5345.namprd02.prod.outlook.com.

--

Lincoln R. Best

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