Create a bee habitat in your backyard and raise solitary bees! Often overlooked in favor of their more famous counterparts like honey bees, solitary bees play a vital role in our ecosystems as unsung heroes of pollination.
Unlike social bees, solitary bees do not live in colonies or produce honey. Instead, they build individual nests in a variety of places such as burrows in the ground, hollow plant stems, or wood cavities. Female solitary bees collect pollen and nectar for their offspring, carefully depositing these provisions into individual chambers within their nests before laying a single egg on top. Once sealed, the nest is left to develop and hatch on its own.
Solitary bees are typically docile and non-aggressive, making them excellent pollinators for gardens and orchards. They are often smaller in size compared to honey bees, with an array of colors and appearances. Some common species of solitary bees include Orchard Mason Bees, Leafcutter Bees, and Carpenter Bees, each possessing distinct nesting preferences and habits.
Protecting and providing suitable habitats for solitary bees is crucial to safeguarding their populations and the integral services they provide.
Choosing the “Right” Solitary Bee for Your Garden
On average, one foraging female mason bee can pollinate as many plants as 60 foraging honey bees! In other words, mason bees pollinating Spring cherries can produce double the amount of fruit than honey bees can. Summer flowers and gardens benefit from leafcutter bees with greater fruit and vegetable yields and superior seed production.
Both mason bees and leafcutter bees forage for pollen and nectar within 300 feet of their nests. Therefore, it is essential to have plants in bloom during the foraging period. In addition to early-flowering edibles, native plants like Oregon Grape are great for supporting mason bees!
Orchard Mason Bees
Select the orchard mason bee to pollinate your spring fruit trees, flowers, and other fruits, including plums, cherries, apricots, nectarines, apples, peaches, pears, kiwis, blueberries, and most nuts.
When temperatures rise above 53 degrees, the mason bee emerges from hibernation. Female mason bees live about 6 weeks, while males only live about 2 weeks. They are one of the first bees to fly in Spring, plus they start earlier in the day and pollinate longer into the evening than their honey bee cousins.
The female builds her nest in existing holes by gathering a pea-sized amount of pollen; she then lays an egg in her hole and seals the chamber with mud from nearby. One tube might house 5–8 egg chambers. By summer’s end, the new eggs develop into adult bees and spin protective cocoons in which they hibernate through winter.
Leafcutter Bees
Leafcutter bees are perfect pollinators for July and August Summer vegetables as well as other Summer-flowering plants such as tomatoes, melons, zucchini, and beans. About ⅔ the size of a honey bee, leafcutters are black with pale yellow stripes on their abdomen. They fly best when temperatures reach the high 70s.
The “leafcutter” name comes from how they collect nesting material. They cut smooth semicircles from non-fibrous plant leaves about ¾ inches in diameter from the edge. Rose leaves are a favorite, as are Epimediums, Twig Dogwoods, Lilacs, and shrub-style Hypericum. To have these holes in your rose leaves shows that you have a healthy yard! Make sure your neighbors are aware of their habits as well—you don’t want them spraying and causing harm to your bees.
The leaf cuttings are cemented together with leaf juices and bee saliva to form a cocoon for the eggs. The new eggs become larvae, overwinter as larvae in their cocoons, and then develop into bees in early summer of the next season. The female’s life cycle is similar to that of the Spring mason bee, but they overwinter as larvae instead of adult bees. They can survive until July as larva and require incubation to mature. Leafcutter bees need 3–4 weeks of temperatures at about 84 degrees to transform into adult bees.
How to Create a Habitat for Solitary Bees
Placement & Preparation
Both mason bees and leafcutter bees can use the same house! Consider it like a timeshare—they do not need to be in it at the same time, but they each require different diameter nesting tubes.
- Mount your bee house on a sunny, warm wall with morning sun exposure at about eye level; best in an area protected from wind and rain (under eaves or overhangs).
- The female bee needs a stable environment for nesting. Once set up, leave your house in place. If you are not satisfied with placement, consider adding another house in a new location and see which one the bees prefer.
- Keep a mud source nearby for mason bees and non-fibrous plants nearby for leafcutters.
- Create a messy palette from the nesting holes. Rather than a uniform look and layout, insert the materials in an irregular design by pulling some tubes or reeds out from the group; place sticks, twigs, or small objects between the tubes or trays to give the bee a “homing” device.
- When you are ready to set out mason bee cocoons, place them behind or on top of the nesting box when daytime temperatures reach about 50–55 degrees Farenheit and blossoms are appearing. Place leafcutter cocoons out in the same manor, but when the daytime temperature is about 70 degrees Farenheit. You will need to allow time for them to emerge from incubation.
Supplies for a Solitary Bee House
While your bee house can be made from almost anything, the nest-building materials must be easy to remove and easy to clean.
- The best materials to use are natural reeds or EasyTear mason bee tubes and reusable wood trays that can be opened and cleaned between uses. Between mason bee season and summer leafcutter season, just swap out the used nesting tubes and replace with smaller diameter nesting material.
- Avoid drilled blocks of wood or bamboo as they are not easy to open or clean; inattention to cocoons leaves them vulnerable to predators, disease, and environmental elements.
- Mason bees seal each egg chamber with mud; clay mud with moderate moisture content best.
- Store mason bee cocoons in the refrigerator; best if kept inside a HumidiBee (cocoon humidifier) within your refrigerator to reduce the chance of drying out.
- Know if you have enough holes for your bees—about one hole is needed per cocoon. You will want about ten cocoons per mature blooming tree.
Timeline & Steps for Mason Bees
Late Winter: Inventory and prepare for spring—do you need more cocoons? Are there enough holes for your bees (one hole for each cocoon)? You are in charge of when to place out your hibernating bees and nesting materials.
Early to mid-Spring release: When your cherry/plum trees begin to bloom, release a portion of your hibernating bees; consider releasing them in thirds to lengthen your pollination season. About mid-April, count how many holes are in use by nesting females. Add more tubes or reeds on top of existing holes if you are filling up.
Late Spring: All bees should be released by May 1st. Check your nesting material to be sure you still have enough space for your nesting females; if 60% of your nesting holes are filled, buy more tubes or reeds and trays. Examine cocoons that have not opened by May 1st to determine if they are still viable. Keep your mud source moist.
Early Summer: By early June, most of your mason bees have expired; take your nesting material out of the houses and store them safely in an ambient temperature garage, shed, or barn.
Fall harvesting: Open your nesting material; separate cocoons from debris by hand and remove pests if present. Store in a cool environment—keep them outside in ambient temperatures for about three weeks; be sure to keep them protected before moving them to storage in 35–37 degrees for winter (refrigerator is best).
Fall & Winter hibernation: Bees are slowly consuming stored fats while in the refrigerator; continue to add water in your HumidiBee. If you prefer to paint or stain your mason bee house, do it now.
Incubation Tips for Leafcutter Bees
These developing bees need to be protected. Place them in the Leaf Guardian bag and incubate them in a warm temperature. This can be done indoors or outside. Maintain a constant temperature of 84°F and humidity ranging between 40% and 90%. It should take approximately 23 days for bees to begin emerging. At a temperature of 70°F, this time may extend to 4–6 weeks.
We find that the Leaf Guardian bag helps to stop pests from attacking the unprotected larvae. If incubating the larvae outdoors, place the Leaf Guardian, with cocoons in it, in a warm, protected place such as under an eave or other covering. Do not place larvae in direct sunlight.
More Bee & Pollinator Resources
- Sign up for “Bee Mail” through www.crownbees.com for reminders on critical timing and care steps, such as putting your bees out too early or too late, missing an important step, leaving your bees to fend for themselves in Summer, or forgetting to harvest your cocoons in the Fall.
- Find out more about helping pollinators at www.xerces.org.
- Join in a backyard bee count with the Great Sunflower Project at www.greatsunflower.org.
- Purchase the Gardener’s Guide to Raising Solitary, Native Bees for more detailed information.