Flower diversity and bees in (sub)urban areas

Does anyone have information or resources on the range and behavior of non-honey bees? It’s well studied how far honey bees will travel to forage and how they share that information with the hive. But how do solitary bees find new floral resources and how large of an area do they visit?

It’s common advice to plant a wide range of native plants for native pollinators. Due to habitat destruction, many oligolectic and solitary bees are uncommon to rare. I have personal evidence that “if you plant it, they will come” and it doesn’t take very long for a wide range of native bees to show up. Are there fringe populations of rare bees in urban areas searching for new habitat?

For example, Macrotera is a genus of small Andrenidae with several species that visit globemallow (Sphaeralcea). Globemallow will happily grow out of sidewalks and glass dumps in downtown Albuquerque and you’d be hard pressed to find a plant that doesn’t have a herd of tiny brown bees, despite a general abundance of cars and lack of ground nesting habitat.


I was able to find this article (not behind a paywall) which I think you’ll really enjoy:


the TL;DR answer is 150-600m, though this is derived from experiments on females’ ability to return to their nest after translocation (in a dark box) within 8 hours of release. The authors mention that individuals released within their observed foraging range were able to find their way home more often. The authors don’t mention -but I think it’s relatively safe to assume- that when in their natural pattern of searching for food, it would be easier to travel further on their own and travel back to nest than it is to figure out where they are after a disorienting box ride to a random place…


I think part of it might be where you live as well. From what I’ve heard, the oases in otherwise arid areas can have an immense diversity of bee species; this is why San Bernandino Valley in Arizona has the highest bee diversity in the US. Perhaps Albequerque is a similar case, so you also see a high bee diversity with many able to survive in the city.


Honey bees, bumble bees, etc (large, strong-flying) can fly farthest, vs. much smaller bees like Lasioglossum. Various studies have found different maximum flight distances. Although, it’s not always likely that a bee will fly near it’s maximum flight range, as there are energy costs in traveling the longest distances for resources. Urban and suburban habitats have been found to be important for wild bee abundance and diversity, although habitats and their surroundings which are overly simplistic ecologically can exclude some floral specialist or uncommon bees. Diversity is increased by connecting or increasing the size of city green space habitats, such as parks, preserves, gardens, and green roofs, and by using native specialist plants and providing nesting resources in habitats. It’s possible there are examples of uncommon bees “trapped” in certain urban areas if that’s what you mean, although I don’t know specific examples. Although generally there are probably few examples of rare bees being found only within large cities, since diversity is often somewhat reduced compared to more natural habitats.


So many good questions here! Surely iNaturalists could help researchers with some pilot projects.


This summer I was doing some bee surveys for the park district and in a couple of sites I did find floral specialists. I suggested to my boss that the district do a program where we try to find what specialists are in which sites and then reach out to the neighbors to suggest that they plant for those specialists in their yards. One of those sites is a small prairie surrounded by neighborhood, but I found out that it used to be used as pasture, a couple of the sites are even remnants.

It’s actually a goal of mine to log a species of floral specialist in my yard.


Researching indigenous bees. Research at Cape Point (Cape Town)


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To the paper linked by @morganic I’ll add this one: https://www.researchgate.net/profile/Andreas-Mueller-48/publication/238364851_Maximum_Foraging_Ranges_in_Solitary_Bees_Only_Few_Individuals_have_the_Capability_to_Cover_Long_Foraging_Distances/links/5a1f20bb0f7e9b9d5e027a7a/Maximum-Foraging-Ranges-in-Solitary-Bees-Only-Few-Individuals-have-the-Capability-to-Cover-Long-Foraging-Distances.pdf

Females of many bees fly not far from nest, and even if they can, it’s costly, so covering a given area in flowers, even small patches of them, is important. On the other hand, bees can come to a suitable habitat “from somewhere”, and some species can quite rapidly increase their range. Possibly dispersion before establishing nest is something different than foraging when nest is etablished. There are quite a few papers showing that cities are surprisingly good place for at least part of bee species, and it’s worth to care for suitable habitat for bees there.
https://www.sciencedirect.com/science/article/abs/pii/S0006320719307761 (!)


On the grounds of my townhouse complex located in South Carolina, I’ve noticed bees sleeping on flowers overnight. I planted this daisy all by itself in an eroded spot in a sea of turf grass.
Given the pollen on the legs–some of these are female so they didn’t go back to their nests.
My favorite flower this year has been red okra put to erosion duty near the neighborhood dumpsters. After planting them I’ve seen the numbers of this bee go up. https://www.inaturalist.org/observations/89936855

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This is the one I’m proudest of hosting and identifying https://www.inaturalist.org/taxa/271677-Perdita-chamaesarachae

Based on all the great articles people have provided, it seems my yard is near the outer edge of a foraging circle that includes wild, undisturbed habitat for many of the solitary bees I’ve observed. Once they find a good spot, they settle in quick and that’s great news for them and me!


I have found 20+ bee species visited weeds and sidewalk edge plantings on a quarter acre near my town house in Pittsburgh. And over a dozen wasp species. I think the rough terrain helps, there are weedy slopes tough to build on near most areas in the city. And it also helps the city is full of back alleyways in neighborhoods without the extra cash to spend on weed killers. A final advantage is parks that do not use pesticides.


Yes, these are the kinds of habitats I mostly visited too.

I know that in South Africa, there are a large number of Bee species you can find very close to or even in the center of an urban area (most of our Bee’s in SA are solitary and do not form typical hives). There are a few taxa though such as the Euglossinae that you only find in unspoilt forest or old growth savannahs in the subtropics, as these Bee’s depend on flowers with deceptive pollination syndromes (i.e the bee ‘mates’ and pollinates the flower tricked into taking it for a female via tactile and scent cues)


Although I mostly know the eastern United States as a region, forest-associated bee species are often also found at the edge of where open areas like meadows meet forests, or in openings within forests. A major factor seems to be the association with sunlight (vs. shade) for flowering plants, similar to your comment. Forests also include multiple nesting substrates.


Not directly about foraging ranges, but about urban bee diversity, and how cities and gardens can provide refugia.

My garden is located in the geographic center of Brooklyn. And while it is large by New York City standards, it is small as most gardens go. The plantable area is less than 230 square meters (2,490 square feet).

I designated the backyard as a native plant garden. As that part of the garden matured, I began to notice and appreciate more and more the insect diversity visiting the plants and flowers. Many of these I had never seen before. I photographed them, and used BugGuide, at first, and then iNaturalist to get identifications.

As my garden grew, I planted more and more native plants. Now nearly my entire property is dedicated to native plants. I’m currently growing over 200 species of plants native to the Eastern United States.

I also manage it specifically as a wildlife and pollinator habitat. At least four bee species nest in my garden. I’m sure there are others, as well, but I haven’t found their nesting sites.

As that plant and habitat diversity and abundance increased, so has the number of bee species I’ve been able to document on iNaturalist.

Year New Species Cumulative Species
2011 6 6
2012 8 14
2013 5 19
2014 7 26
2015 7 33
2016 3 36
2017 2 38
2018 2 40
2019 4 44
2020 6 50
2021 5 55

As of this year, I have documented 55 Taxa (iNat “Species”, which means Subgenus or lower taxonomic rank) in my garden:
Epifamily Anthophila Species in Flatbush Gardener’s Garden

Jarrod Fowler’s Web site is the go-to resource for specialist bees in my region:
Pollen Specialist Bees of the Eastern United States

Based on his work, and other novel research, Cornell University and the New York State Natural heritage Program came out with a guide for gardeners:
Creating a pollinator garden for native specialist bees of New York and the Northeast

With these resources in hand, I am choosing more plants to benefit specialist bees. I don’t know if they will show up, but my garden has shown me: If I plant it, they will come.


That’s great you documented so many species in New York City. I wonder if any were new to previous species lists for NYC. I see you’ve documented some specialist bees too. That’s also notable since it’s often more difficult to document a high diversity of bees including specialists in highly urbanized centers like NYC. Like large NYC parks and greenways, gardening helps support urban bee populations and show that even urban cities can be valuable habitats. Having enough green space/bee habitat in the surrounding landscape outside any individual habitat like a garden is also a limitation cities often have. Yet, gardens have many advantages in being customizable, and the more green spaces which are added to cities help improve overall city green space connectivity.


Thanks for sharing! What have you seen in terms of bee predators and parasites? Any robber flies, Ripiphoridae, or Philanthus?


All of the above. :-)

I’ve seen only a handful of Macrosiagon limbatus. I don’t know what their ecological relationship is to bees.

I’ve seen at least four species of Asilidae, half this past year. Again, I never thought of them as bee specialists, just opportunists. When I’ve seen them with prey, it’s been another fly.

I get a lot of Philanthus gibbosus. “Beewolf” makes their relationship clear!

I have a few kleptoparastic bee species. Coelioxys octodentatus has been present for at least a decade; I’ve also seen a handful of C. sayi in recent years. I’ve observed Triepelous lunatus almost as long, though less frequently. I get Nomada reliably every year. I was excited when I first observed Bombus citrinus in my garden, indicating robust bumble bee nesting.

I’ve a dozen occupied nesting tubes this year. I want to cage them and winter them over to see who emerges next year. I suspect many of them are wasps, not just bees. And I expect/hope to see some kleptoparasites and parasitoids, as well.


I don’t know if any reach NY https://bugguide.net/node/view/6695

Mine have white stripes!


the area I live is urban and I found 9 species of bees