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.