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Mason bee block

Posted by bugdoctor 5 CO (My Page) on
Mon, Jul 28, 14 at 23:17

Zach, this is in response to your question about orchard mason bee blocks. Mason bees are supposed to be the premier pollinator, far more efficient than honey bees! I like to reuse the blocks I have made, so this is an attempt to help show you how I have gone about keeping them around.

I take a block of wood about 8 to 11 inches in length and cut the back of it off about a half inch lengthwise (if its a 2x6 of untreated wood). If its a post (4x4) like i have pictured, I cut about 6 inches worth off. then I take that and cut about an inch of that block off, giving me a 5 inch block and a 1 inch matching piece (seen below the roof here).

I then drill holes of 1/4 to 3/8 in. completely through the 5 in. block. I then cut natural parchment paper that I buy from Whole Foods (though there are probably some at the local grocers) to 6 inch lengths and cut that sheet into fourths. This will give you about 2.5 inch x 6 inch strips of paper. I roll those onto a screwdriver or a pencil, depending on how big the holes are in the block.

Here is the paper sticking out the back

Then I fold the parchment paper rolls over in the back, which later serve as a handle to pull the filled tubes out.

Then I screw the back on and often run some duct tape around the back plate so that no parasitoids crawl in and to keep the water out.

From the front this is what the bees see

I then pull the tubes out and put them into a small jewelry box with a pencil sized hole in the side. I tape this to the bottom of the blocks or set the jewelery box close by. The emerging bees will stick around if they have nesting sites, which you will provide with the clean block filled with parchment tubes.
They are really neat to have buzzing about in the spring. I put the blocks out when the flowers on the fruit trees are beginning to open. All of my neighbors have some kind of apple or crab apple, plum, or pear so there is plenty for them to nectar from. They just need the temp to reach around 75 or 80,so I put them where they receive morning sun.

They only live for about 4-6 weeks. Once they are done flying, I take the boxes down, bring them into the basement to complete development. In the fall, you can pull the tabs and get the tubes with the larval cells separated and see the females from the males as the girls are bigger.

I don't have any pictures of these later steps, but hopefully will follow up on that this spring.

For those who are made of money, you can buy cardboard tubes and inserts on Amazon and other internet retailers, but you wouldn't have the fun of making them and thinking about what you have provided them.

I dont know if this helps clear anything up, but hopefully a picture tells a thousand words!

Simply search for mason bee block videos and you will find all kinds of variations of what I have made (and much neater than mine I am sure).
I hope this speaks to your inner carpenter/Builder Bob!

Follow-Up Postings:

RE: Mason bee block

  • Posted by ZachS z5 Littleton, CO (My Page) on
    Tue, Jul 29, 14 at 20:50

I guess it didn't want me to post a reply the first time...

Thanks Doc, I appreciate the pictures. I can read instructions 10,000 times and STILL do something wrong, so pictures are definitely useful lol.

I really like the design of that one. I have looked up bee blocks on the Google but I like the easy access/tube retrieval with the cover on the back of yours.

So, I have some questions:

Do the mason bees only have one generation per year? They emerge, reproduce and the 2nd generation emerges the following spring?

Also, do they ever emerge in your basement? How do you know when to put them outside so you don't have an orchard bee city in your house lol.

RE: Mason bee block

I have had issues with GW lately failing to email me when subsequent posts to threads come up, so you're not the only one it doesn't like!

The mason bees have one generation per year. It makes them so easy to have around.

You certainly don't need to bring in the bee cells to your home if that's not your thing. If you don't, there could be several predators that will mine little holes into some of their tubes and attack the developing larvae. Some suggest waiting til fall to bring them in, but if I remember, I just grab the blocks that are filled up and store them in the basement once the adults are no longer visiting the blocks (usually around the beginning of June). Bringing them in greatly reduces the risk of predators. The adults are only out from late March to early June. Once you've got all your planting done for the season, but the end of May early June, then it's time to start to monitor the boxes for adult visitation drop off.

Yep, we've certainly had a few bees in the house! If you forget them in the basement, they will emerge by about mid April no matter the temperatures, so you gotta get them outside by the end of March. If a couple do emerge earlier, I put the freshly emerged adults into the refrigerator with a cotton ball soaked in sugar water 2:1 water to sugar. The cold slows them down and the sugar water sustains them for a few days to a few weeks. I then put the entire little box in the fridge until it looks like Mother Nature is cooperating, and providing them with blossoms to visit. To avoid any issues, I try and put the boxes and bee cells out when the flower buds on the fruit trees start to look like they are about to open.

I wish I had some pictures of the larval cells. They are like little bullets with mud on either side.

As a note, the roofs on the boxes for mason bees are totally not needed, though I think the little workers appreciate a little rain cover. I've seen people stack 2x6 blocks in their yard without any rain cover or roof, and they still keep their bees happy.

In the late fall, you can often find folks selling starter mason bee pupal cells on Craigslist and EBay for around 20 bucks. Of course you can purchase them from online sellers as well. I never have had that many blocks where I had a bunch of surplus bee cells, but maybe I'll build a few more boxes this fall to increase the reproduction opportunity next spring. I'm not in it to make money, but I would be willing to donate some starts to someone wanting to give them a try if they produce enough next spring.

Zach, as much as you seem to like insects, this little cheap project should be on your to do list! Of course, I'm happy to answer any questions that may come up along the way.


RE: Mason bee block

  • Posted by ZachS z5 Littleton, CO (My Page) on
    Wed, Jul 30, 14 at 13:19

Thanks for all the info, I appreciate it. I got rained out of work today (sucks) so I built me a bee block! Pretty much exactly like your design, just tweaked a little.

I only had a 3/8 in long bit, and the holes are about 5 1/2-6" deep. It has a removable back plate like yours, but I just used a scrap of fence picket left over from the roof. Do you think they will use it if its hanging from a tree or do they prefer it to be on a solid foundation? Let me know how I did.

Cheap? Hell Doc, I didn't spend one dime on this, I just used old scraps I have layin around! It is perfect.

I am actually just a nerd for all sorts of things and I love the outdoors. Insects are really convenient to observe since they hang out in my front yard. I was working on a biology degree for a while, but switched to natural resource management/park ranger certification since I cant afford to be in school forever. But, biology is a passion of mine, the natural world never ceases to amaze me.

Anyways here's my first block. How many should I put out the first season? And, is there anything I need to change/adjust?

 photo IMG_8479_zps0e6a32fd.jpg

 photo IMG_8482_zps10fcaeeb.jpg

RE: Mason bee block

You are right on with the block Zach. I think it looks great. Hopefully your new mason bee colony will use it this spring.

I'm not sure if they will use a nesting site that is free hanging. I read they do not like vibration, so I have always put them on a fence or hung from a tree but leaning on the trunk so it doesn't move about too much. Could be worth trying if you have a protected site though. One thing for sure, they need morning sun to nest in the block.

The number of blocks you make and set out depends on the number of starter bees you begin with. If my memory serves, most people sell around 10-15 or 20-25 pupal cells as a starter pack.

I started out with just a few bees, like 6 females and 4 males. In the beginning, I tried to give them as many options to choose one of my blocks as possible, so I had a few blocks made up with various size holes for them. If there are many options, the females seem to choose holes away from occupied holes first. I think it would be best to provide at least twice as many holes as you have females, but more would be ideal. After the initial season, you'll know how many females you might have and can prepare a few extra blocks if needed during the winter months. However, in the beginning, I think it best to start small and build, so that you're not swamped trying to figure out what to do with them all and see if it's something you think you would like to continue.

I too have no money in the blocks or insect hotels other than time and parchment paper. I use scrap wood for all of them! Besides, they are a real conversation piece when guests come over. If I tell them they are for bees, people panic. If I tell them they are for native pollinators, people say how great it is. Funny!

You deserve some good karma for providing some nesting sites for the native pollinators. Kudos!

RE: Mason bee block

  • Posted by ZachS z5 Littleton, CO (My Page) on
    Thu, Jul 31, 14 at 15:39

I hope so. We have lots of fruit trees, several apples, pears, quince. But, they only flower every other or every third year. We have a huge stand of chokecherries though, so, maybe they will like those.

I read recently that are two different mason bees that people typically sell. One is native east of the Divide, the other, west. Does it matter which ones you get you think?

I think I will just try to mount somewhere. With the winds we get, I don't thing there's a way to hang it that it won't get blown all over the place.

I did make another, this one a little larger and with 2 different size holes. They are shallower, 3 1/2" seep since I used the 4x4 longways, so we'll see how it works. The 1/4" holes are about a 1/16" short of actually going all the way through, so, IF they decide to use those ones, they will have to overwinter in the garage or the shed, since there's no way for me to get them out.

I think this will be all for now, that nearly 40 holes for them to use, if they chose to do so.

I painted them to sort of protect the wood, hopefully make it last a little bit longer, though, I kept the area around the holes unpainted in case they are picky about that.

 photo IMG_8484_zpsa508a51a.jpg

That's the new one ^ and below is how I mounted it with a couple zip ties on a bamboo pole.

 photo IMG_8485_zpsf149396e.jpg

I sure could use some good karma lol, thanks!

RE: Mason bee block

If I were a female mason bee I'd raise my babies in there! Looks good to me!

I got my starter bees from someone here in Boulder that was selling them on Craigslist, so I never worried about the east or west species. I guess if I were buying them again, I'd make sure I got the species for east of the continental divide. I think these are the blue ones, just off the top of my head. The red ones are from the west coast if memory serves, but you might want to double check that I don't have em backwards. If you can wait til Oct or Nov to order, there is a good chance you can find them locally. I think the Denver botanical gardens sell them too.
I can ask the Colorado Bee Keepers Society to ask members if they have starters for newbies, but that won't be until the fall.

I too am going to make some up in the near future. I like your bamboo pole idea!

In my opinion, you should put them out without papers in the holes to season them before next spring. For whatever the reason, in my experience they don't use them the first season. Maybe getting them out now will circumnavigate that. Just a thought.

Keep us updated!

RE: Mason bee block

I put a block out in June that was a little late for the Mason bees but we now have 4 or 5 tubes filled from Leafcutter bees and they seem to be still building. Very similar to the Mason i believe but uses leaf cuttings to build the larva chambers instead of mud. I read they emerge later in the spring so you might try and put your block out now if you'd like to collect any of them. Hope this helps.


RE: Mason bee block

  • Posted by ZachS z5 Littleton, CO (My Page) on
    Sat, Aug 9, 14 at 11:54

(Sorry for being such a stranger, had to be out in Montrose last Thursday-Sunday, and every time I come back I get swamped with work and too tired to internet haha).

Thanks for the tips and advise guys! I will put them out now, and leave them up through the winter. I will keep my eye out for mason bee larva, I never thought of Craiglist for bees!

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