Keep Those Bee Hotels Buzzing

Host:

Ah, May in North Carolina. Flowers blooming, temperatures trending towards warmer nights and a tease of summer in the air. There’s a certain buzz about spring, one that we’ll all be celebrating on May 20^th on World Bee Day. This international day puts a spotlight on the master pollinators and their friends and gives thanks for the vital role they play in our ecosystem.

To celebrate World Bee Day, Farms, Food and You sat down with Elsa Youngsteadt of NC State’s Urban Ecology Lab to learn more about bees in North Carolina, why they are important and how we can help foster their continued population with gardens and bee hotels.

Youngsteadt:

My lab started in 2018, and we’re an Urban Ecology Lab. I’m especially interested in plant-insect interactions in urban environments and insect ecology in cities. So we study bees, and ants, and potentially other insects to be determined.

And one thing we’re particularly interested in is how urban warming affects insects because, of course, insects are, you can’t see air quotes in audio, but insects are known as coldblooded animals. Their metabolism, their body temperatures depends partly on the environmental temperature. So urban warming makes their bodies get hotter and their metabolisms increase. And so just the very urban environment could change the way their bodies work, the way they do business in the world, the amount they need to eat, when they’re able to be active, everything about their life. And then there’s also the potential that if cities are doing this to them, future warming outside of cities, due to global climate change, could have similar effects. So we’re interested in cities for their own sake because most humans live in them. And then, also, as potential indicators of what’s going to happen outside the cities in the future as the rest of the climate catches up to current urban temperatures.

Host:

If you’re wondering why Youngsteadt spends so much time worrying about ecology and insects in cities, it’s because insects, especially pollinators, help sustain urban environments.

Youngsteadt:

So there are a few reasons that pollinators in cities matter. A lot of the time, we think about them being really important in agricultural systems outside the city. They’re out there pollinating our fruit, and berry, and net crops, but there also is a good amount of agriculture happening in cities and right around cities. So a lot of the stuff you grow in a home vegetable garden, whether it’s blueberries, or zucchini, or pumpkins, or even tomatoes benefit from having bees visit those flowers. At least some tomato varieties will have bigger tomatoes or more tomatoes if those flowers get visited by insects than if they’re just left to their own devices. Things like cucumbers and zucchini must be visited by insects to actually set fruit or to actually make that vegetable. Same goes for blueberries.

Anyway, I could list plants forever, but a lot of what we grow and eat in our home gardens depends on insect pollinators. And then, a lot of the remnant, natural vegetation in urban areas also relies on insect pollinators to sustain its life cycle. About 80% of all plant species in the world use animal pollinators. And most of the time, when we say an animal pollinator, we mean an insect. A lot of times we mean a bee. Every now and then, it’s a bat or a hummingbird, but bees are the powerhouse pollinators. So all of that vegetation in cities, in our green spaces, and parks that we’re not actively manicuring needs pollinators to visit its flowers so that it sets seed and can actually complete its life cycle.

Host:

Creating spaces where bees can find nectar isn’t just about helping pollinate. It’s also about survival for the bees themselves.

Youngsteadt:

So bees in particular need nectar and pollen throughout their life cycle. The adult bees are drinking nectar as their energy drink to fuel their flight throughout the day. Something like a bumblebee is often only less than an hour from starvation. They have such a high metabolism when they’re flying that they’ve got to be refueling constantly. So they need places to make pit stops, to be able to drink some nectar. And then what they’re really out there doing is not just feeding themselves, but collecting loads and loads of pollen to take back to the nest, to feed the next generation. So flowers are really important. And I think that’s probably the advice we hear the most often is like plant a pollinator garden, have flowering trees, flowering shrubs, some native perennials in your landscape that provide food from now. I shouldn’t say now. That provide food from anytime in late February, up until first frost.

The very first ground nesting bees start showing up in the Piedmont of North Carolina by the end of February. And they need food as soon as they show up. So having insect friendly flowers available in the landscape the entire growing season is one thing. Thin bees don’t just need food, they also need a place to nest. And for different bees, that means different things. About 70% of the native bees in North Carolina, of which they’re about 560 species total, so about 70% of those actually nest in the ground.

And then, bumblebees are also their own weird category. Queen bumblebees spend the winter alone without a colony. And so they need places that they can tuck into the leaf litter or some forest edge duff to over winter. And then, when they come out in the spring to find a place to make their colony for the year, it depends on the species exactly what they’re looking for. Some of them like to nest in old bird houses that haven’t been cleaned out. Some of them nest in old rodent boroughs underground. Some of them nest just under grass tussocks at the surface of the ground. People will occasionally find them in the corner of a compost bin or tucked into some insulation and somehow got into the corner of an attic or a shed. So they vary, but the thing that they all have in common is a little mess around the edges. There’s got to be something that’s not perfectly manicured and tidy for them to find a place to tuck in.

So I’ve said 70% ground nesting, plus bumblebees, which aren’t a lot of species, so a small percentage. And then, the rest, the other 30% or so are the cavity nesting bees. And those are the ones who will live in things like bee hotels. So their natural nesting substrate is hollow stems or beetle holes in dead wood, any natural tunnel. They don’t drill it themselves, but they find preexisting nooks and crannies and tunnels, and use them to build their nests. And so for them, again, leaving a little bit of mess, some untrimmed perennial stems if you have a garden is a good thing for them. Leaving dead wood around if there’s a place you can leave, it is a good thing for them. But then also, bee hotels are a fairly popular substitute. It’s basically like a birdhouse, only for bees. And you put in either some of your trim stems or purchase reads or drilled blocks, blocks of wood that you’ve drilled holes into. And any of those can substitute for natural nesting substrates that have been cleaned up in our urban environment.

Host:

Besides adding a cool feature to your garden, bee hotels give places for solitary bees to lay their eggs, and house them for the next year while they mature.

Youngsteadt:

So most of the bees in North Carolina, they’ll collect nectar and pollen, and mix it together and make it into a little loaf in the nest. And then the female bee will lay an egg on that little loaf. And then she will partition it off into its own chamber in the nest. If it’s something like a bee hotel where she’s just building in a tunnel, she’ll go to the back, make her pollen provision, lay an egg on it, and then build a wall. She’ll never see who hatches out of that egg. Then she’ll repeat. She’ll make another pollen loaf, which is another several dozens or even hundreds of foraging trips depending on who she is and what kind of pollen she’s collecting, lay an egg, build another wall, and repeat until that nest is full. And then, if she’s still strong at the end of that, maybe she’ll find a new nest and repeat.

So depending on the bee, one individual solitary female bee might lay 4 to 12-ish eggs in her lifetime. I don’t remember the top end record, but it’s not a lot. She really needs two to survive to replace her and the father bee. So there should be some extras there, which is good because of times you’ll have some succumb to diseases, or parasites, or too hot or too cold nest conditions. So that’s what the nest is for, is the safe place for those bee babies to develop. The eggs that hatch out will then eat that pollen provision that their mom let for them. They’ll pupate, and then they’ll just wait. Depending on the kind of be, they might be in there, basically, a whole year.

A lot of bees just have one generation per year. So the bees who are just coming out in the early spring, a lot of them only have one generation per year. So they’re going to do all of their pollen and nectar collecting now, lay their eggs now. Those larvae will eat all of their nectar and pollen in the next few weeks. And then they’ll just be waiting for until next spring. So even though we only see the adults out flying around for a few weeks or a couple of months, the immatures are still there underground or inside that nest tunnel the whole rest of the year, even when we’re not seeing them.

Host:

Creating a Bee Hotel is easy and fun. Youngsteadt and her team developed a step-by-step instruction booklet that you can find on her lab site titled “How to Operate a Successful Bee Hotel.” You can Google it or find the link on our Podcast webpage: https://cals.ncsu.edu/farms-food-and-you/.

Beyond supporting native bee and wasp populations, Bee hotels are also entertaining and provide opportunities to learn about pollinators close up. By installing these nesting sites in your yard and observing their residents, you can learn about native pollinator diversity and how the variety of food and flora we enjoy in our gardens, markets, parks and green spaces are linked to pollination services provided by hotel residents.

The booklet also includes information about maintaining the bee hotels to ensure a healthy bee population.

Youngsteadt:

What you don’t want to do is just make a bee hotel and stick it out there and forget about it because most of the species who will live in it normally are living dispersed in the landscape. They’ll find a hole in a piece of wood over here, or a hollow stem over there. And then, by the next year, that nest isn’t really attractive anymore and the next generation will go somewhere else. Whereas, in a bee hotel, you’re concentrating a lot of neighbors in one place. And if you don’t clean it out every couple years, any diseases, or parasites, or mites that they had tend to accumulate. So I’m not saying it’s a bad thing to put them. We do have evidence that a well-curated bee hotel can increase bee populations, but it’s not something necessarily to take lightly. And you may decide that it’s easier to leave some untrimmed stems in the corner, or some dead wood somewhere else than to actually put in this thing and have to take care of it.

So that’s my recommendation. Have flowers throughout the growing season and have nesting resources by leaving some mess. If you’ve got some bear soil, leave it undisturbed. If you have natural cavity substrates, leave them undisturbed. If you don’t, you can add them to your landscape, and some insect hotel.

Host:

Thank you for joining us on Farms, Food and You. This podcast is a product of NC State Extension and the College of Agriculture and Life Sciences at North Carolina State University. If you would like to support the show, please share this episode on social media and leave a review on your podcasting app of choice. Let’s talk soon!