The Joys of Orchard Mason Bees

  1. Several people were curious when I casually mentioned that I raised Orchard Mason Bees. So, I am starting a thread where we can share our experiences and tips with each other. Surely, I cannot be the only one who raises them.

    These small, gentle black bees are hardcore workers in the garden. Although they have a short lifespan, they are big urban pollinators of tree and cane fruit.

    I started raising them way back in the early 90s. My first experience was ordering from Knox Cellars, north of Seattle, WA. At the time I lived in Pennsylvania.

    Before I relate my experiences with them, I'd like to paste some information about them, from the Washington State University Agricultural Extension:

    The orchard mason bee (Osmia lignaria) is a gentle beneficial insect that has potential as a pollinator of apples, cherries, and other fruits. It is found throughout most of North America, particularly in wooded areas but often around homes in towns and cities.

    Homeowners sometimes become concerned when they see the bee entering cavities under shake siding or investigating nail holes or other cavities in wood during March through early June. These are not destructive insects, since they do not excavate holes in the wood, though they will clean out loose debris.

    The orchard mason bee is slightly smaller than a honey bee and a shiny dark blue in color. The actual size of the bee depends largely upon the size of the hole in which it grew. Males are smaller than females, have longer antennae and an additional tuft of light colored hairs on the face. Females have hairs on the underside of the abdomen, called the "scopa", adapted for carrying pollen.
  2. More from the Washington State University Agricultural Extension:

    Nesting Habits and Lifecycle

    The female uses existing holes in wood for a nest. She chooses holes slightly larger than her body, usually 1/4 to 3/8 inches in diameter. The bee first places a mud plug at the bottom of the hole, then brings in 15 to 20 loads of nectar and pollen which she collects from spring flowers, including apples and other fruits. If you watch the bee closely as she enters the nest, you can see the pollen on the underside of her abdomen.

    When the female has provided a sufficient supply of food for the larva, she lays an egg and then seals the cell with a thin mud plug. She then provisions another cell, and continues in this fashion until the hole is nearly full. Finally the bee plasters a thick mud plug at the entrance. Some wasps and leaf-cutter bees also build nests in such holes but their nests can be distinguished from the orchard mason bee nests by characteristics of the plug. The plug of the mason bee is always rough while the wasp prepares a smooth plug. Leaf-cutters seal the holes with chewed-up leaves.

    The female orchard mason bee lives for about a month and can produce one or two eggs each day. The larva hatches from the egg after a few days and begins to eat its provisions. When the pollen-nectar mass is completely eaten in about 10 days, the larva spins a cocoon and pupates within the cell.

    Near the end of the summer the bee transforms to the adult stage but remains in the cocoon throughout the winter. In the spring, when the weather has warmed up sufficiently, the males begin to emerge by chewing their way out of the cocoons and through the mud plugs. The females, which are almost always in the inner cells of the tunnel, emerge several days later. One or two weeks may be required for all the bees to emerge during cool weather.

    Females mate soon after emerging, then begin nesting in 3 to 4 days. The bees forage on a number of different flowers. In wooded areas, they seem to prefer ballhead waterleaf. In urban areas, pieris, dandelion and Oregon grape are commonly visited, in addition to cherries and apples.
  3. More from the Washington State University Agricultural Extension:

    Most Gentle

    The orchard mason bee is non-aggressive and will sting only if handled roughly or if it should get trapped under clothing. It is less objectionable than the honey bee as a pollinator in urban areas and should be encouraged. Efforts are being made experimentally to develop large populations of these bees to use as a supplement to honey bees for fruit pollination, much as the alfalfa leafcutting bee was developed for alfalfa seed pollination.
  4. Things I have learned....Nests
    Using the tube and liner method (as sold by Knox Cellars) has been the most sucessful. After trying pretty much every method commercially available in the past 20 years and monitoring morbidity rates, I feel the tube and liner method is the way to go. For one, these do not hold in moisture. Moisture encourages fungus and I've seen mortality rates as high as 40%. There is a neat method that has plastic nesting blocks that come apart, but these do not breathe, and the cocoons bloom with fungus. The drawback with a solid wood block with drilled holes is if the bees in front die, nothing will get out, and that could be 7-9 bees per hole. Plus there is no way to clean drilled blocks sufficiently.

    Things I have learned...Sun and Warmth
    Sun and warmth are not overrated Right now, our bee house is situated on a west facing brick wall. The sun hits it about 10am and then the bees come out. I've tried it on an east facing wall with less success and on a west facing fence with very little success. You need the warmth of a wall and sun as early in the day as possible to keep the bees active.

    Things I have learned...Who is eating my bees?
    After all the eggs are laid and the adults have died, there is good reason to cover the front of the nesting straws with wire mesh. All sorts of things find your sleeping baby bees delicious. We have woodpeckers year round that will try to peck out a tube to get at the cocoons. Also, mice will visit, rats (Ugh), as well as parasitic wasps who will want to lay their own eggs on the cocoons so their own young will have food. So, cover the front of that nest up.

    Things I have learned...Ready to hatch, yet?
    For the past 10 years, I make it a practise to remove the straw liners from the previous year unwrap and remove the coccoons. This I do in January. I can see the dead ones by putting them on top of a large flashlight lens. Dead ones look hollow. Remove these to avoid spreading any viruses or pathogens. Then pop all the cocoons in the top of your nesting box, while you wait for Spring and hatching time. Make sure to put fresh liners in your straws and load up the bee house.

    Things I have learned...Bees get thirsty
    You will need a water source close to your bees. They will travel ¼ mile to find water, but then they may decide to set up house over there. We have a bird bath in the backyard and that takes care of it.

    Things I have learned...Bees will work for you
    I have the bees mainly for the pollination of my blueberries, goji berries and myrtleberries. The hatching time corresponds with spring blooming of apples, cherries, plums and peaches. You will notice an increase in yield with a healthy population of Orchard Mason Bees nearby.

    I truly love these little workers and you will too. Please share your experiences and don't forget to post pictures.
  5. Here is our current bee house and a pic of one of the cocoon chambers. About 100 bees hatched last weekend. They all poop a little bit right after they hatch, that is the white stuff you see.
    beehouse.jpg coccoons.jpg
  6. This has to be one of the most fascinating threads I've seen in a long time- I was just looking at a mason bee house the other day, and wondering if I should put one out to attract them. Thanks for all the neat info!
  7. :love: Thanks so much for posting this, Jburgh!

    Amazing!!! Cant wait to see more!
  8. You definitely should get a house. If it gets colder than 20 degrees in the winter, you will need to store your cocoons in the refrigerator during that time.

    When I lived in PA, I had to do this. My cocoons were wrapped loosely in a few paper towels. I put them in a paper bag and then added a damp paper towel on top. Without the dampness, their little bodies will desiccate and they will die. Every week, I changed out the damp paper towel. The bees typically spent November to March in the fridge...depending on the weather.

    These babies really paid off and I had over 40 pounds of Italian plums on one tree on a regular basis.

    Now that I live in an area that rarely gets to be colder than 25, the bees are outside year round. When we get some unseasonable arctic air, I put them in the unheated garage for a few days.

    It is fun to see dozens of them sunning on the fence. I'll take pictures this weekend...hopefully some extreme close-ups with the macro lens.

    And seriously, they do not sting. I've had them land all over me and not one sting, ever. They are docile.
  9. I think I have these too. I have something about half the size of a Honeybee, maybe smaller and either black or dark blue. I haven't been able to get a decent picture though due to their size and speed.
  10. Echoes - I bet you have Orchard Mason bees. I have to wait for pictures until it is sunny here - then they will sun themselves on the fence. Still rainy, bah!
  11. It's official. I love bees more than I love bags. This is amazing, I love love love learning about bees.
  12. Finally, some sun and... OMBee!
  13. Awww.....Irishgal :love:


    LOVE :love:

    That is the cutest, that made my day.
  14. You two are sweet!