Most of what we read in the news about declines in bee populations focus on (non-native) honey bees. Yes, those populations are suffering declines from the combined impacts diseases, habitat loss, pesticide use and other factors. However, there are nearly 4,000 bee species in North America, and many of them are dealing with the same pressures and threats as honey bees. In addition, honey bees are social insects, living in large collaborative colonies of workers and queens. The vast majority of bees in North America, however, are not social, and they succeed or fail on the backs of single moms.
Solitary bees – bees that don’t live in colonies – are all around us, but they go largely unnoticed. Many escape our attention because of their small size, but others are as big as or bigger than honey bees. Solitary bees can vary greatly in their diet preferences. Some are generalists, feeding on nectar and pollen from a wide variety of flower species. Others have much more narrow diets, feeding only from sunflowers, for example, or other categories of flowering plants.
Most solitary bees in prairies live in underground burrows, though others live in hollow plant stems or similar spaces. In colonies of social bees, the work of gathering food, maintaining and defending the home, and feeding and caring for the kids is split between hundreds or thousands of bees. In the case of solitary bees, the single mom does everything. In most cases, she finds a likely spot, digs a burrow and prepares it for eggs. Then, she flies around the neighborhood in search of the kinds of flowers she can collect food from. As she nears the flowers, she’s likely to encounter males of her species, who basically spend their entire lives buzzing from flower to flower, hoping to find females to mate with.
Assuming the single mom can find food nearby, she returns from foraging with a load of pollen and nectar, which she combines into a ball of sticky dough. She places that in a cell within her burrow, lays an egg on or next to it, and seals up the cell. Then, she takes off to repeat the process: find food, mix it together, lay an egg with it, seal up the cell. Later, the eggs will hatch, and the larvae will stay in their cells and feed on the dough balls provided for them until they grow into adults and leave the nest.
As you might imagine, life isn’t easy for single mom bees. They have to gather food for themselves and their kids, while fighting off overly-enthusiastic males with only one thing on their minds. When they aren’t out finding food, they are building and provisioning baby rooms or sitting vigilantly at the entrance of the burrow, defending it from marauding wasps or other threats. After mother bees have filled their burrow with eggs-in-cells, they seal up the whole nest and fly away, hoping for the best.
Single mom solitary bees have difficult lives, but there are ways we can help them. First, we can help ensure the availability of nesting sites. Some ground-nesting bees need areas of bare ground, and many others need at least access to the soil without having to fight through a dense layer of plant litter. Similarly, stem nesters would appreciate it if you didn’t chop down all of last year’s plant skeletons, especially those of raspberry, sunflower, rose, leadplant, and other plants with hollow stems. Providing this kind of nesting habitat is important in prairies and other natural areas, but also in backyard gardens and other urban areas. Because solitary bees aren’t aggressive toward humans, there’s no downside to sharing your yard or garden with them (and, as pollinators, they’ll work for their housing).
Perhaps more importantly than housing, what bees need most is food. The key to supporting strong bee communities is plant diversity. A prairie or garden with lots of different kinds of flowers will support lots of different kinds of bees. Specialist bees will be able to find the particular flowers they need, and generalist bees won’t run out of food when one kind of flower stops blooming, gets eaten by insects, or is wiped out by disease. Early spring can be a particularly difficult time for bees to find food because of the relative scarcity of flowers at that time of year. Boosting the spring-time abundance of both native wildflowers and flowering shrubs in gardens and natural areas can be very helpful.
In prairies and other large-scale habitats, it’s important to think about the flight range of bees. Honey bees can travel up to several miles to find food. Most solitary bees are considerably smaller, however, and they may be limited to a range of a few hundred yards or less from their nest. During their nesting season, bees will need to find everything they need to survive and supply their nests from that relatively small circle of habitat. The availability of abundant flowers of many kinds within that circle helps ensure that bees can find food throughout the season. If a large area surrounding a bee’s nest is mowed or grazed intensively, it is left stranded with a nest in the middle of a food desert.
If you’re a landowner or land manager, think about your property from the perspective of a single mom bee. Pick a few spots on your land and visit them every few weeks to see what the abundance and diversity of flowers looks like. If a bee was nesting where you stand, could she find what she needs for food within a short distance of that location? Are there times of year when it’s hard to find abundant flowers? If so, can you tweak your management or implement restoration strategies to make more flowers available? Are there places where bees can find bare soil for nesting, or is there a layer of thatch covering the soil across your whole site? Burning, intensively grazing, or haying portions of your land each year can help reduce thatchiness and help ensure bees’ access to soil. However, creating patches of prairie habitat representing a full spectrum of vegetation structure types (tall/dense, short/sparse, mixed-height, etc.) will be of maximum benefit to both bees and other insect and wildlife species.
Single mom bees deserve our respect and admiration. They build and prepare their nest, seek out and harvest food while dodging predators and lustful males, and provision their eggs with food and a safe place to grow up. Oh, and along the way, they also pollinate and help ensure the survival of the majority of plants on earth. It seems only fair that we should acknowledge their work and do what we can to help them out.
While the vast majority of native bees are solitary bees, some are social as well, including bumble bees, some sweat bees, and others. Bumble bees, in particular, are very important pollinators because of their size and mobility as well as their willingness to visit many different kinds of flowers. As opposed to honey bees, whose colonies can survive the winter intact, all bumblebee individuals except fertilized queens die at the end of the growing season. Those fertilized queens overwinter and then become single moms in the spring. Once the queen’s first brood matures, those bees take over the foraging work and take care of the queen. You can learn much more about solitary bees and other native bees here.
Many thanks to Mike Arduser and Jennifer Hopwood for reviewing this post for accuracy. Any remaining errors are mine, not theirs.
Wow, I learned a lot. My parents are beekeepers but I never really paid much attention tot the solitary bees.
“Similarly, stem nesters would appreciate it if you didn’t chop down all of last year’s plant skeletons”
We’re looking for a compromise between leaving everything completely standing all winter through next spring and complete cutting and removal of deal plant material. Anyone mow stuff down and leave thatch? Or is that too much disturbance?
Also – the standard question about negative effects of fire… yes, creating bare ground, but also burning up stems and the larvae inside. I’m anticipating that the tradeoff, or management strategy, is (what else?) keeping things “patchy” in time and space!
Hey Adam – first, on your second question. Yes, of course, patchy is always the right answer! On the first, I think standing dead material would be much more valuable than mowed down thatch – and not just for bees, but for other species that use that structure has cover. Not that thatch is bad either, but it just provides a different kind of habitat. Voles will certainly appreciate it, for example!
Sorry – I neglected to mention that we are talking about fairly highly landscaped Midwestern settings (e.g. Rain garden), not the vast unpopulated stretches of the great plains :) As always, I try to use it as an opportunity for education… the challenge being people who see it only through their car window, once.
Thanks for this great post.
I know in a residential setting, it can be a real challenge to avoid neighbor complaints and city notices to mow your weeds, and often they don’t particularly care if those ‘weeds’ are supposed to be providing refuges for insects and animals that need such things. When we lived in the city I tried to compromise by making sure that the edges that neighbored our neighbors, or were highly visible, were mowed Or plant short-stature species in those locations that ‘look’ like traditional landscape plantings, such as groundcover-type roses, iris, etc. Then in a more internal portion of the backyard, but still a little distant from the house, we piled cut stems over top of branches to form a small-scaled ‘shelter’/compost pile. It usually worked pretty well except that every year or two it would have to be destroyed and rebuilt to cut out any saplings that would get a good start there.
Besides bare ground, one might consider using hollow stems and other materials to build a hotel for native bees and wasps. Location (close to flower gardens) and maintenance (eliminating ant infestations and moldy conditions) matters, but it’s enjoyable to see many different species use these sites. See for example http://www.mnn.com/your-home/organic-farming-gardening/stories/how-build-hotel-wild-bees
Great point, Patrick.
Amazing writeup, and very timely for me. During the restlessness and boredom that comes with winter, I was toying with the idea of starting up a honey bee operation, but wrestled with the fact that they’re an introduced species (my small suburban Minneapolis postage-stamp of a yard has been completely converted to native-only landscaping). I’m thinking I’ll just stick to what I’ve been doing and continue to increase diversity and quality of habitat (as small as it is). One thing i’ll need to monitor more closely is the availability of bare soil; all of my beds are currently heavily mulched with leaf litter and plant trimmings to build rich soil. I’ll definitely be collecting those plant stems this spring to create some solitary bee nesting sites.
Good for you, Andy. I think you’ll enjoy seeing all the different kinds of bees that show up.
Insects are definitely an underappreciated part of conservation that deserve more attention from nature enthusiasts.
Here is a video I took last year of pollinators on common boneset (Eupatorium perfoliatum) in my garden.
Even a small native flower planting can attract a large variety of interesting pollinators.
Agreed! Cup plant. Culver’s root, and goldenrod species are a few more that are pretty easy to grow and attract lots of pollinators.
great article chris,
I’m a beekeeper on our native prairie ranches and sometimes I worry that the honey bees are in competition with the native pollinators. is there any evidence of this that you know?
On Tue, Feb 14, 2017 at 3:38 PM, The Prairie Ecologist wrote:
> Chris Helzer posted: “Most of what we read in the news about declines in > bee populations focus on (non-native) honey bees. Yes, those populations > are suffering declines from the combined impacts diseases, habitat loss, > pesticide use and other factors. However, there are near” >
Hi Wade, this is a topic that is much debated. From what I understand, the complexity of trying to study the interactions between honey bees and native bees has prevented any solid answer so far, and there are studies that have pointed in both directions (impact and no impact). An educated guess would be that there has to be some kind of impact, but whether it’s significant enough to push for keeping honey bees out of important natural areas is still in the air. Because of the potential risks, we’ve made the decision on our Platte River Prairies not to allow honey bee hives, but of course there are still hives in the neighborhood, so we still see honey bees in portions of our prairies.
If we were to compare this to how it functions with larger animals, I feel like at the end of the day, competition is competition. I imagine it must always be a large energy expenditure for an animal to secure good foraging and nesting sites. That said, I would imagine the stresses would be much higher in an urban setting with fragmented wild areas, versus a larger preserved area.
I have missed you I forgot to let you know I changed my email when we moved last year. glad to reconnect. Was a caretaker of an environmental area had lots of prairie I cared for after retiring from NRCS. now fully retired to help son and daughter with grand daughter. living in urban area. So come spring need to devote some of my postage stamp back yard to more diverse cover. Love your thoughts and Ideas will enjoy reconnecting! Lombard illinois which is sub burp of Chicago have fox in back yard due to 90 feet of trees along power line and 2 prairie path railroads. I need some names of very shade tolerate flwrs fo my Black locust filled back yard have about 8 very old trees? thoughts get sun but trees are 80 ft tall mowed now not blue grass too shaded got some bare patches. Need to get seed on ground soon? thoughts please?
As you are probably aware, most seeds will need to cold stratify for at lease 30 days; i’m not sure how your weather is in Chicago but over here in Minneapolis we’re already flirting with spring temps (unprecedented during my lifetime, btw, but that’s another discussion…) so i’d say get those seeds down asap. I believe Chicago’s plant diversity is similar to what we have here, with the presence of higher conentrations of more eastern species. Please anyone correct me if i’m wrong, but off the bat it sounds like a great opportunity for some Asters (Symphytrochium spp), Zigzag Goldenrod (Solidago flexicaulis), Sweet Joe Pye (Eutrochium purpureum), Canada Wild Rye (Elymus canadensis), Wild Golden Glow (Rudbeckia laciniata), Brown Eyed Susan (Rudbeckia triloba); there are a ton of options, but these might be a good start if you’re looking for pollinator support. One plant that doesn’t need to cold stratify are the Mountain Mints (Pycnanthemum spp), so that might be a good quick starter for you. Definitely do a bit of research first, and please realize that many of these species can get pretty…”enthusiastic” about spreading, so if you’re wanting a more manicured look for what sounds like is a smaller project, i’d be a bit selective.
Thanks Andy for the ideas as I would not have thought of Sweet Joe Pye as I thought it needed more sun i like it appreciate comments. I’m a wildlife Biologist so looks is cool with me I just have to worry about neighbors and since it is tucked in way back near timber of right of way I think I will be OK and only about 100 by 30 feet at the most in size
It’s commonly propagated error to state there are about 4000 native bees in North America. This is incorrect. The true number is closer to 5200. You can find a full list here:
This is a fascinating post. I learned so much. The solitary bees I most often see are leaf-cutters. I spend most of my time around the water and boats, and leaf-cutters adore the small clamshell vents on the outside of boat hulls. There’s nothing quite so amusing and touching as watching a little bee bring bit after bit of leaf to a boat, clamber into the vent, and set up housekeeping. It’s a bee’s version of any port in a storm, I suppose.
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I really needed to write on struggling single moms… This has motivated me tnx
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