Native Pollinators with Heather Holm

Heather Holm is an amazing author on native pollinators and has an incredible Instagram Page sharing her love of native pollinators, bees, and wasps.

In this episode, we talk about the need for protecting native pollinators, competition from non-native bees, and what we can do for our local ecosystems.

Learn more about getting your own Rebel Garden at ABetterYard.org.

Transcript

0:10

All right, good morning everyone. Welcome to the Minnesota Gardening Podcast. I am absolutely honored to have Heather Holm with us here today to talk native bees and upper Midwest bees to be a little more specific on things. So Heather, thank you so much for joining us. Thanks, Brad. It's great to be here. So you've got four books, if I've counted it correctly, on bees and native bees, and you do a lot of your own photography, and they're just absolutely gorgeous bees. I gotta add native bees and wasps, and I'll ask you for the difference between there, just so everybody knows. But can you give everyone kind of a little sense of your background and how how you got into this love affair with the bees and wasps? Absolutely. So my love affair with pollinating insects started uh from the plant side of things. So I actually my educational background is horticulture and biological sciences. And it was just prior to moving to Minnesota, I really started to uh reinvigorate, I suppose, my interest in insects and and since then have really done a deep dive, you could say, into understanding the many of these different insect groups that visit and pollinate flowers and trying to highlight those important relationships. So I, in a sense, I am bridging the two gaps bet the gap between the plants and the insects themselves and trying to communicate those interactions. Got it. And you do just an absolutely amazing job of that in your books and on your Instagram uh feed and wherever wherever people can find you. So I just appreciate everything you're doing there. So let's let's dive in. So we talk a lot on a Minnesota Gardening Podcast about native plants and native ecosystems and making sure that we are working in the Doug Talamy sort of world of making sure that we are supporting our local ecosystem. And so could you give us from your perspective why that is important for pollinators and just the world? Absolutely. So, yeah, native plants essentially what I'd like to say is they form this with insects, they form a really critical, robust foundation of complex food webs, much like Doug Talamy talks about. So just the plant-insect interactions alone, many of those are specialized interactions. So with the 512 species of native bees that occur here in Minnesota, close to 30% of them have these specialist relationships with native plants. So if a female bee is just collecting pollen from a certain kind of plant. It could be a single plant genus. For example, we have dogwood pollen specialists here in Minnesota. We have goldenrod specialists. So that in itself is why incorporating more native plants, whether it's a home garden or through increasing diversity in a larger ecological restoration, is going to boost up the diversity of insects because of those relationships. And then how do those insects boosting up those uh relationships between the insects and the plants, like how does that affect the greater ecology of our landscape and of our neighborhoods and of our regions, and and why is that important? Well, insects, yeah, besides that plant-insect interaction, you also have to think about the insects that are herbivores, the ones that are consuming either foliage, plant foliage or seeds. And those insects in turn are fed on by various types of birds and mammals. So it's that foundation that I talked about is really creating the diverse restaurant for all of the other organisms in a complex food web that rely on either insects directly or they're consuming some kind of mammal or bird that is relying on a largely insect diet. So even at even in our small urban yards, we by planting native plants, we're not just creating habitat for pollinators, we're we're helping to sort of restructure those lost and complex food webs. And so as we are doing that, what's the best way to, and I promise we'll get into uh other uh other bees and pollinators and those kinds of things in a bit here, but so what is the best way in from your perspective for boosting up that local ecosystem? Like what kinds of, does it need to be 100% native plants? Is that where we need to be from your your work that you've been doing? Is it some balance in between there? And then also what do you, as we're talking native plants, what do you consider as a native plant? Does it have to be historically here and within you know five miles of your home kind of thing? Or is it a regional or where how do you how do you help define that? Those are really tricky questions, Brad. So a native plant for me is something that's occurring uh locally or regionally, and so if you really want to plant something that maybe grows within two to three hundred miles, that is probably your best bet. But many people are planting and experimenting with plants that are native to Iowa or south of Iowa, and and that's fine as well for a home garden. You you just have to make more careful considerations, particularly when you talk about uh ecological restoration. That's a complete set of parameters. But for the home landscape, um having you know, primarily mostly native, Doug Talamey's work in regards to the insect and plant relationships for songbirds, he his research has shown that 70% is generally the cutoff. So a garden that has at least 70% native is going to be uh meeting those objectives of building those complex food webs and supporting diverse organisms locally. So if you have less than 70%, that's okay as well. But that is uh a very good goal to work toward if you are interested in planting native plants. Got it. So a landscape full of you know hydrangea and boxwood are not really gonna help help our local ecosystems here in Minnesota, so all that much. And so, because and the reason why I asked that question was because I was doing some research on two two different trees, and one was catalpas and one was uh little leaf lindens, and just seeing where they're native to and what and catalpas are like origin are native native to just a small bit in southern Illinois, like at the confluence of two rivers. And so I was fascinated by that piece because at the cat catalpas, we have a lot of pollinators that are buzzing all around the catalpas that are around here. They're blooming right now as we record this in June of 2024, and so it it was very interesting the same way with uh little leaf lindens that are also not native to this. We've got big leaf lindens that are native to Minnesota, but uh not so how like how do from a pollinator perspective, how do you balance that that may have some ecosystem services to it, uh, but may not be native to an area? What do you think about that? Yeah, those are interesting examples. And as you said, you know, catalpa is native to North America. It surprisingly for uh flowering native flowering tree has a really small historic range. And they're pretty prevalent now in Minnesota, and they often seed prolifically. My neighbor has a catalpa and I have catalpa seedlings all over my yard. Oh, really? But yeah, the the flowers, you know, they they have those large, almost orchid-like flowers, and uh a number of different bee genera do visit the flowers. So you are providing some some benefit of you know something blooming this time of year, which we tend to be in a lull between that first flush of all the spring flowering uh perennials and shrubs into when we you know ramp up into our summer, summer mode of perennial flowers. So some of those flowering trees can play an important role even if they aren't uh strictly native to our uh region. The lindens I'm not in favor of with doing ecological restoration. The European linden is now uh starting to invade natural areas and becoming thicker than buckthorn. So I tend to recommend people plant the the Native American basswood. Now those those flowers are blooming in typically in July, they're pendulous, they're white, they're fragrant. Surprisingly, not a lot of daytime visitation to those flowers. I've you know investigated many, many basswood in bloom and have yet to see many bees visiting basswood. But a study out of Michigan showed that a lot of the pollination is happening uh at night, and the basswood flowers ramp up their nectar production later in the afternoon to service nocturnal pollinators, includ uh mainly moth. So uh in Michigan, the American basswood is primarily pollinated by moth, and that may be the case uh here in Minnesota as well. The European linden flowers are extremely attractive to uh non-native honeybees. So people often think this is a great flowering tree to plant for pollinators, but it really is primarily servicing one non-native species. Got it. We will absolutely come back to that. I've got that in my list of things to talk about here this morning. But let's dive into just native native bees and wasps in general. So, what why do you think that specifically bees and wasps are native bees and wasps or something that we should, as we're choosing what plants to plant in our landscape, as we are looking to the future, what what do people need to know about bees and wasps and why are they important to our landscape as opposed to other types of pollinators, and why do we need to make sure that we're supporting them? Sure. So the the common thing that many people probably already know is the the importance of having a diversity of bees in our environment to help pollinate the food crops that we depend on. So many of the fruit tree, fruit-bearing trees, the small berries, summer vegetables that we grow in our garden, tomatoes, etc., those are all reliant on insect pollination to produce the fruit that we are dependent on to consume. I often look at the importance of pollinators from the the conservation side of things. So pollinators, I'm talking about them in general as a group of insects, are pollinating more than 80% of flowering plants on Earth. And some in some regions that's percentages higher. And without that successful pollination, any type of plant is not going to produce fruit or seed and allow for that plant's uh reproduction through seed seed production. So we really need pollinators to continue to uh re have allow plants to reproduce to make our landscapes more diverse and obviously resilient. And going forward with climate change, real resiliency is is extremely important. And that that is resiliency is built into having um diverse ecosystems. And what kind of things can a home landscaper home landscape person do for native bees and wasps? Like what are some things that we should be looking at making sure we have available in our landscapes for those friends? Absolutely. So some of the basic principles, if you want to plant for these pollinating insects, you want to have a diversity of flowering plants blooming throughout the growing season. That's that's a real basic requirement. You can layer on top of that a diversity of different flower colors and flower shapes or forms. Because all of these various different insects come in different sizes, they have different tongue-lengths, and they're flying at different times through the growing season. So having that flower restaurant, as I call it, open 24-7 throughout the growing season is going to likely support as many pollinators as you can that occur where you live. The big one, of course, is pesticide use, right? The more we can reduce pesticide use in home landscapes, then the more we're going to create a welcoming environment that's not harmful to these pollinating insects. So those are some key things that a homeowner should think about if they if the intent is to draw in and support pollinators in their home garden. And what kinds of things do people need to consider for native bees, like for habitat specifically for native bees? Is it with for ground dwelling and for stem dwelling? Like how how what do people need to think about that way? Right. Yeah, I just covered the the food, right? The flowers, but they need a place to live too. And some folks maybe aren't even aware that these native bees are either nesting in the ground in our gardens or some in some kind of cavity above ground. So in if you have very well-drained soil, anything between a loam and a pure sand, then you likely have a fair diversity of native bees that are nesting right in the ground in your garden. And most of those bees are solitary, so they don't uh defend their nest, they won't sting you, so you can easily welcome them into the garden by either leaving patchy spots of uh not bare ground or specially vegetated, not using landscape fabric or other things that would create a barrier for those bees to get into the ground and excavate their burrows. And then for the ones that are nesting above ground, which make up uh I'm a minority about 30%, they're nesting in pre-existing holes in wood. So a hole in a standing dead tree, a hole in a log lying on the ground. Some of the smaller species are nesting in old plant stems. So one of the really easy things you can do is when you cut your plant material back, leave some plant stem double, anywhere from eight inches in length to 20 inches. And that stubble cut off by you, you know, snipping off the top of it, is what creates an opportunistic opening for some of those smaller stem nesting bees. Yeah, and watch, and I don't remember where I read an article about stem nesting bees and how there was a study that was done following deer around in a native area, and so they were the deer, they were following the deer, and excuse me. But they were following the deer, and as the deer were browsing, this the bees that were following those deer were invading, were using the cavities created by the deer. So how how you said 30% are above ground? I didn't realize that was the statistic on there. And so, like, how should people be handling spring and fall in their landscapes for this specific thing? Like when, when should they cut things off? Does it really matter all that much? Should they just leave leave stems? Like, what do you what do you recommend? Yeah, the the timing isn't as critical, and I think people get really worked up about doing harm and trying to figure out the best time. For what I do in my home landscape is I leave all that perennial plant material, the seed heads, up for the winter. I leave, you know, I allow the birds to come and um feed on the seeds. And then in in spring is when I go in and cut down, usually with garden scissors, I just chop away and let that material fall back into the garden and selectively leave some of that perennial flower stem stubble. There are certain plants that don't work well, you know, you wouldn't want to leave daylily stem stubble because that's really soft and will degrade, break down in less than a growing season. So some of the plants in the Aster family, the Asters, the Goldenrods, the Black-eyed Susan, the cone flowers, they have really strong fibrous flower stalks. And those would be ones you would want to consider cutting off and leaving some stubble. Now, to your point about that study with bees following around uh deer browsing. So if you're doing anything such as cutting back live growing flower stalks mid-summer to make the plants shorter, they call that the Chelsea chop, for example, then still that act of cutting off the top of the stem is what's going to provide the opening for a bee potentially nesting within that stem. So as far as timing, if you do what I just described that I do, cutting all my old plant material down the following spring, then bees will be nesting within that stem stubble for the next 12 months. If you uh remove everything or are pruning mid-summer, then you would want to leave all that material indefinitely as well, because just doing the Chelsea chop, you might have a bee nesting in that cut stem. So you really just have to be aware of your your garden stewardship practices and how that relates to a bee's life cycle and what if you may be providing those opportunities or not. Got it. And just so everybody knows, Chelsea chop is uh is a method of uh making of working to keep plants generally smaller and bushier, a lot of times perennials like sedum and different kinds of things like that that tend to get a little floppy in the fall. If you cut them back in in mid-summer, they'll they'll continue to grow and will will be shorter and a little more bushy plants and that kind of thing. So it's a really good thing to do that way for some folks. I don't do anything like that because I do lazy lawn care and landscape and that kind of thing. And I I make it uh the least amount of work possible for things. So all right, so we've got a couple minutes left here, Heather. I want to uh address a couple different topics. One is that tension that we talked about a little bit before between non-native and native bees. Can you talk about that a little bit as to how that affects our local ecosystems and how non-native bees affect native bees and that type of interaction? Sure. So any species, whether it's a plant or insect introduced into a new environment where it's not native, can have consequences, not always, right? So we do have a number of introduced bee species out of that 512 I mentioned that occur here in Minnesota. And a handful are fairly harmless. They've been here for many, many decades, likely accidentally introduced. Many of them are solitary cavity nesters that were imported in wood shipping crates accidentally. And they tend not to have too much of an ecological impact. But the the tension that I think you're referring to, Brad, is the the non-native honey bees, which are you know a long-standing species that was introduced in as early as the 1630s to North America. Um, it's it's wrapped into a whole industry and hobby of beekeeping. But the big difference between uh a honey bee and uh an introduced uh solitary bee is is the numbers. And so a hive has 10,000 to 50,000 bees living within it. In Minnesota, they're typically managed by humans. And so placing a hive anywhere can have either a small or significant impact, depending on the amount of food resources flowering plants near that hive. And so a lot of the new research is demonstrating that that competition for resources. Can be really significant if not enough adequate floral resources are available. And then the second concern is the transmission of pathogens and diseases from honey bees to our native bees. So it really sort of calls us into action to be very mindful and thoughtful about where hives are being placed, how many hives, and understanding the potential impacts to the native bees, which are some at risk of extinction, right? And a conservation concern, whereas this managed species, the honeybee, is is not at risk of uh going extinct. There's no conservation concern for that species. So often people don't understand the sort of the dynamics of what what bees we should be saving and what bees we should be maybe managing further. And so what are the the potential outcomes of of this are if so if someone has a uh honey bee uh nest, a hive on or near their property, does that push out the uh the native bees? Does that does that like what what happens, what are the next things? Like there's a lot of potential outcomes, but like in reality, what what kinds of things are happening today? So a hive can one hive for the three months in the growing season, June, July, August, can collect the equivalent amount of pollen as a hundred thousand solitary native bees. So that's a that's a significant amount of food resources essentially that are getting extracted by a single hive of honey bees in in a landscape. So we if we put if we're saturating hives even in the urban environment, right? If you had a hive in your backyard in in the city, you don't have enough property in the city or flowering plants to provide adequate resources for that hive that won't be impacting surrounding resources that native bees depend on. So it really is context specific, right? If you had a if you had a hive in a rural area and you have planted two to five acres of flowering plants to feed the bees in the hive, then your impact would be reduced to surrounding native bee species. So it's really dependent on the situation. We also have to keep in mind in Minnesota we have a federally endangered bumblebee species that's uh you know at risk of extinction. And so the question is should we be adding more and more hives in in urban, suburban areas where this endangered species is largely present and somewhat abundant if we know that the impact could be could really greatly impact that endangered species by having too many hives? So that leads me perfectly. You did a great segue there for me, into our our good friend the Rusty Patch Bumblebee, the state bee of Minnesota, and just specifically about Rusty Patch, why why is Rusty Patch Bumblebee important and what can people do specifically to help that little friend? Yeah, isn't it awesome we now have an official state bee? Then it's an endangered species, and here in the metro or an outstate, it's not impossible for someone to find and observe a federally endangered species. And so that really illustrates how much we can do back to our beginning of our conversation, right? The importance of planting a diversity of plants to support the rusty patch and other pollinators. If people want to know specifically what to plant for the rusty patch, the U.S. Fish and Wildlife Service, the federal agency overseeing endangered species, has a really great comprehensive plant list. And so it will detail a number of native plant species to grow through the growing season. Many of them are appropriate for gardens that you can plant to help support the Rusty Patch Bumblebee. Got it. Beautiful. And I'll put links to that in the show notes that everybody can find at MinnesotaGardening.com. And Heather, it's just been an absolute pleasure chatting with you today. I just appreciate all of your knowledge and just we didn't even weren't able to make take a deep dive into your incredible photography and just how exactly you do that and how your home landscape works. So if if people are interested, I'll put a couple links to some other podcast interviews I've heard with you that are just awesome. They're just really well done. So just thank you so much for being here. Where can where's the best place to people find you? And can you I haven't even had you talk about your books. Will you talk about your books real quick just to make sure we're putting a good plug-in for them and I'll put links in the show notes for them as well. Sure. People people can find me through my author website, and that also includes a number of resources, plant lists, etc. And the URL is pollinatorsnativeplants.com. And the four books you can learn more about on that website as well. I have a book on pollinators of native plants was my first book. The second book is Bees, so that's a deep deeper dive into uh identifying bees and learning what to plant for a specific genera. And then the wasp book, if you really are curious about wasps, you can check out. Yeah, and the wasp one is so very cool. It's great to see like all those pictures of, and we also didn't get to get into there much. So I feel uh a second episode coming on sometime in in the future to talk about those kinds of things. But Heather, thank you so much for being here again, and I appreciate your time and have a wonderful rest of your day. Thanks so much, Brad.