What are they?
Mason bees are a native pollinator of early flowering plants. They come out in early spring, when the temperature is around 12-14°C. Mason bees are a non-aggressive, solitary bee that does not build hives or have a queen. Mason bees are 75% more effective per bud at pollinating than honey bees and stay in a smaller area, making them ideal backyard pollinators.
What do they pollinate?
Mason bees mostly pollinate fruit trees or other early spring flowering plants. Apples, plums, and other early flowering fruits and plants benefit from mason bees. They do not usually hang around into summer, and aren't as useful for vegetable gardens.
When do I put them out?
Mason bees will stay in a dormant state until the temperatures are around 12-14°C and they can survive outdoors in that state until around -18°C. While you can bring them inside and store them in a shed or a fridge, it's not necessary. If you do store them in a fridge, make sure you keep them on the door of the fridge and put a wet cloth, paper towel, or small glass of water beside whatever you are storing the bees in to make sure they don't dry out. While the cocoons are waterproof, the bees inside still need to breath. Keeping them on the door of your fridge ensures they get the airflow they need to survive until they come out of the dormant state in spring. If you keep them in your fridge, don't keep them past the end of April at the absolute latest. The bees inside have a set amount of energy and if they stay dormant for too long they can use up their energy stores and die off without hatching.
When do I clean the cocoons?
Mason bees will lay their eggs for 4 to 6 weeks after coming out of their cocoons. The eggs then hatch within 4 days, eat the pollen-nectar food source the parent bee left for them, and spin themselves a cocoon. The bee in the cocoon grows into an adult bee by early September. Once the bee inside is an adult, you can clean the cocoons. We recommend cleaning the cocoons and boxes mid-late fall, October or later, to ensure the bee is fully grown in it's cocoon.
How do I clean the cocoons and why should I?
Mason bee cocoons are waterproof but delicate. Fill a small container with a 5% bleach to 95% water mixture and drop the cocoons in. Gently roll them around in the water for a few minutes and pull them out to dry. This will kill off any parasites or pests that may affect your bees.
The single-use tubes can be hard to get unrolled. Soaking them in cool water for a while before trying can make them easier to get into.
How do I get started?
If you have fruit trees in your yard, chances are you already have mason bees. You can start by simply making sure they have a place to lay their eggs. Mason bees like to lay their eggs in holes around 5/16" in diameter and between 3-6" long. While you can simply grab a block of wood and drill out the proper hole size, we recommend making sure you are able to clean it out at the end of the season. Cleaning the bee house keeps pests such as pollen mites from making a home and killing off all your bees. You can do this by purchasing premade reusable blocks, or drilling out slightly larger holes and filling with parchment paper or cardboard tubes. Tubes can be bought pre-rolled or rolled yourself.
If you aren't sure you have mason bees, you can buy bee cocoons at your local gardening store. We carry boxes of 10 (5 male and 5 female bees) to get you started.
Where do I put the house and what type of house should I use?
Put the house at least 4 feet off the ground in a location that gets plenty of sunlight. Ideally under cover to keep any nasty weather off. Mason bees usually stay within 200-300 feet of the location they hatch from, so keep it within that distance of what you are wanting them to pollinate. Do not bury the house in the trees they should be pollinating but a good 6-10 feet away at least.
Mason bees aren't picky with their houses. As long as the hole is the right size and the location is good they'll use just about anything. They do prefer holes not made in cedar blocks, but will use them if that's what's available. We do recommend that you have a door or something over the front of your house to make it more difficult for predators like woodpeckers to get in.
Single-use tubes vs reusable blocks.
Both the single use tubes and the reusable blocks are good options.
The tubes are generally made out of cardboard or parchment paper, and are designed to be discarded after use. Houses that use the tubes can be great as once a tube is filled, it can be removed and replaced without disturbing the rest of the house. Full tubes should be removed from the house and stored somewhere cool over winter. You can choose to unroll the tubes and clean the cocoons inside, or fill the house with new tubes and place the old ones as close as possible for the bees to hatch out of.
Reusable blocks are, as the name implies, reusable. The blocks are designed to come apart to allow access to the holes for cleaning. The blocks we carry are made with corn plastic, meaning they will eventually biodegrade. The blocks must be cleaned out every year to ensure no pests move in and take over. The blocks are easier to get into and clean out compared to the tubes, and can be cheaper overall as they don't need to be purchased as often. When putting the blocks back together we recommend wrapping a strip of electrical tape or tight elastic around the block to ensure it stays tight together. Avoiding gaps helps keep pollen mites or other pests from slipping inside.
Any other questions you want answered about Mason bees? Give us a call at 250-390-3669, email us at thebackyard@shaw.ca. or stop by our store during our normal operating hours.
