Top 5 Reasons Bees Aren't Nesting in Your Bee House
"Why aren't my bees nesting?" is one of the most common questions we receive from our bee raisers.
We definitely understand how frustrating it can be to take the time to create safe nesting habitats for cavity-nesting bees only to have them fly off and nest somewhere else. We've been in this situation ourselves from time to time!
First a question— Have you signed up for BeeMail? It's the best way to receive seasonal tips and tricks to help you be as successful as possible and troubleshoot a variety of solitary bee related issues!
Next, please be patient. Emergence is temperature-dependent and varies from region to region and year to year. Once bees do emerge, it can take up to two weeks before you'll see bee activity at your bee house. Females have to mate, find a safe place to nest, and find and collect pollen, nectar, and clay-rich mud or leaves to build their nests. Bees also start their nests at the very back of the nesting cavity and can be hard to see when working in this area.
Pro Tip: You can take a flashlight and peek inside your nesting materials at night. Females sleep facing out in the nesting materials to protect their eggs. If they're inside, you'll see their little faces peering back at you! Just don't do this too often, or they may fly off due to being disturbed too often.
Now, before we jump into the Top 5 Reasons Bees Aren't Nesting in Your Bee House, it's important to remember that bees are wild animals, and we can't (and shouldn't) expect them to nest in our bee houses just because we want them to. Sometimes we can do everything right, and they will still decide to nest elsewhere for reasons unknown. It's entirely likely they are nesting somewhere in your yard, just not in your bee house.
Pro Tip: Look for signs that bees are nesting around your yard and garden! Check hollowed-out plant stems, holes in decks or siding, between bricks in sidewalks, and cracks in raised beds or foundations. Don't worry if mason or leafcutter bees take residence in your siding or deck; they use existing holes and will not cause any structural damage.
1. Females will sometimes rest in or near their nesting cavities in the early morning or around dusk
2. Mud-capped ends
3. Yellow pollen marks around nesting cavities
Fortunately, in these cases, they are still pollinating and reproducing nearby. Over time, you may see more and more of these fantastic pollinators in your yard, garden, and, eventually, your bee house.
So, if it's been two weeks since your bees have emerged and you still haven't seen any activity in your nest, then various factors could be at play in this scenario.
1. Lack of mud or soft, deciduous leaves to build their nests
Do your bees have everything they need to build their nests?
There's a reason we call them mason bees! Mason bees belong to the family Megachilidae, known as the architects of the bee world. Females build the walls of their nesting chambers and secure the openings out of mud or other "masonry" products.
Because mud is vital for mason bee reproduction, females will not nest if they do not have a reliable source nearby (within 25 sq. ft.). However, not just any mud will do! Mason bees prefer to use mud with a high clay content or the consistency of modeling clay. Read our Importance of Mud article to learn more about what mud to use and where to install the mud source.
Leafcutter bees also belong to the Megachilidae family, but they use leaves instead of mud as their primary nest construction material.
Female leafcutter bees protect each nesting chamber with a protective shell of cut leaf and flower pieces in the summer. Because leaves are vital for keeping the developing bees safe, females will not nest if they do not have a reliable source nearby (within 30 sq. ft.).
Leafcutter bees can use the leaves of almost any broadleaf deciduous plant to construct their nests. However, they prefer soft, flexible leaves and flower petals, such as alfalfa, clover, buckwheat, roses, peas, lamb's quarters, lilac, redbud trees, or hostas.
There is no need to cut the leaves and bring them to the bees! Cut leaves will quickly wilt and does more harm to the plant than the minor cuts from a leafcutter bee. As long as there is a reliable source within 30 sq. ft., the bees will have no trouble finding and cutting what they need.
2. The presence of lawn and garden chemicals
Bees (and other beneficial insects) are sensitive to chemical scents from lawn and garden treatments and will often fly off in search of more suitable nesting habitats.
What's tricky is that even if you refrain from using pesticides in your yard and garden, they may still be present due to the highly mobile nature of these harmful chemicals. Unfortunately, this means even if you avoid using chemical treatments, the wind may still carry pesticides and chemical scents into your yard from neighboring lawns and gardens.
So, if you are having trouble getting bees to nest in your yard, try reducing your pesticide usage. If you already have a pesticide-free yard and garden, then share your knowledge with your neighbors. Asking your neighbors not to spray while your bees are nesting can be difficult, but it's important. We've created ready-to-print materials to help you get the conversation started.
3. Insufficient floral resources
Did you know each female mason and leafcutter bee can visit up to 2,000 blossoms a day? Take a peek at your open blooms. Do you have enough pollen and nectar resources to support the pollinators in your garden? Are the open blossoms close enough to your bee house? Remember, solitary bees only fly in a 300-foot radius from their bee house, so long trips from the house to open blossoms may deter bees from nesting.
You'll also want to make sure you provide a diversity of native flowering plants that bloom continuously across the entire growing season—struggling to figure out what to plant? Check out our Native Plants and Consistent Blooms article to help you identify the best native plants for your region and act as your guide to incorporating native plants in your lawn and garden.
4. Improper House Installation
A sturdy bee house or hotel mounted to a solid object (like a post, home, or fence) is the foundation of safe nesting habitat. Solitary bees prefer a house that protects them from the wind and rain.
Orientation: Bees are cold-blooded and need the warmth of the morning sun to get started. We recommend you select a site that is south to southeast facing.
For mason bees, if you live in a cooler climate that rarely gets above 60°F/16°C in the spring, consider installing your bee house in a spot that gets sun exposure throughout the day. On the flip side, if you live in a hot climate that regularly sees spring temps above 70°F/21°C, make sure your bee house sits in the shade during the afternoon sun.
For leafcutter bees, if you live in a hot climate that regularly sees summer temps above 90°F/32°C, consider installing your bee house in a spot that sits in the shade the majority of the day.
Just remember, if you place your bee house in a shaded area, don't hide it behind branches. The bees will have an easier time orientating themselves to your bee house if it is easy to view from a distance.
Location: Install the bee house on a sturdy wall, fence, or post -bees do not like swinging in the breeze. Mason and leafcutter bees only fly about 300ft (100m), searching for nectar and pollen, so place the house near open blooms.
Additionally, we've found that bees will sometimes fly elsewhere if it is windy while they're selecting nesting sites. If you live in a consistently windy area, we suggest installing your bee house in an area sheltered from the wind and recommend releasing your bees in the morning of a day with low projected winds.
Height: At eye level, about 5ft (1.5m) off the ground to protect the bees from small predators, like mice or ants. Plus, these bees are fun to watch!
Pro Tip: While we don't recommend moving your bee house while the bees are flying, if you do need to move it for some reason, do so at night when the bees are in their nesting cavities. Relocating at night gives the bees the chance to reorient to their new surroundings in the morning.
Both mason and leafcutter bees use temperature as cues to emerge and trigger the different stages of development.
Spring mason bees hibernate as adults and are ready to emerge once daily spring temperatures are a consistent 55°F/13°C or above. So, make sure you don't release your mason bees until daytime temps reach this temperature!
Summer leafcutter bees need average daytime temperatures of 75°F/24°C or above. Like mason bees, be sure you don't release your leafcutter bees until daytime temps reach this temperature!
Climate change leads to warmer winters, earlier springs, and increasing the number of days with extreme heat and cold. Given the relationship between bees and temperature, you're correct to assume that abnormal weather associated with climate change can influence bee productivity from year to year. Read Climate Change: It's Bad for Bees to learn how to help your solitary bees during extreme weather.
We hope we've been able to help you troubleshoot why the solitary bees in your yard and garden aren't nesting in your bee house! If you've read through this and noticed areas you could improve, GREAT! If you've read through this and learned that you're doing everything right and still don't have bees nesting in your house, don't lose hope! The beauty of solitary bees is that each year produces a new generation of bees that will emerge and look for the perfect nesting habitat you've created!
Final Pro Tip: Research suggests that mason bees are attracted to pheromones left behind from previous nesting seasons. Try our InvitaBee™Plus+ Mason Bee and Leafcutter Bee Attractant, designed to mimic these pheromones and lure bees to artificial nesting sites –such as bee houses.