Making tunnels for mason bees

Whether you are on a budget, or wish to recycle paper to test for mason bees, here’s a how-to photo-montage:

Mason bee parcel-paper nesting straws

Mason bee nesting straws made from parcel paper.

It takes less than a couple of minutes to make one tube + then you block one end with moist mud from the garden.  It’s a great evening activity in winter months and an opportunity to educate young people about nature and the marvellous events that occur in spring.

…and here’s proof that it works:

Osmia rufa (mason bee) nesting in paper straws

A mason bee – Osmia rufa – nesting in home-made parcel paper straws.

When you unroll the tubes to access the cocoons in the autumn to clean out anything that will prevent their emergence (like dead cells, mites or parasites) a perfect tube will look something like this :

Mason bee cocoons in paper-nesting straws

Mason bee cocoons in home-made paper-nesting straws – before and after unrolling the paper.

In the image (above) you see that nectar does seep/wick into the paper, however the lower part of the image shows that the cocoons will successfully develop without any problem.

Just one note of caution - as in natural tunnels, any mason bee cells located paper-straws, cardboard tunnels or reed tunnels will be subject to the attack of Chalcid wasps after the spring. 

This then means at the end of May or beginning of June when the female bees have finished nesting, you should gently move the completed blocked tunnels out of reach of these solitary wasps. You can put them anywhere warm even in the house so that the developing larvae eating the pollen inside their cells are protected (for example, I put them inside my bedroom on a high shelf, out of the way). 

They develop perfectly in the summer warmth of the house and the bonus is that mason bee pollen mites (not the same as bed or honey bee mites) won’t multiply in constant dry warmth, so you’ll have less of them when you check the tunnels in the autumn.

However, if you leave the nested tunnels out in June you may find this:

Chalcid wasp kill young mason bees

Chalcid wasps kill young mason bees – note white holes in paper a sign that wasps have eaten larvae and emerged.

So time to help the bees, but thoughtfully.  Go find some parcel paper or recycle those old office envelopes !

About Paul B

This is my little blog on solitary bees that I have been running for nearly 5 years - I hope you like what you see and do please join in with your comments.
This entry was posted in nesting habitats, paper straws, Questions & Answers, solitary bees. Bookmark the permalink.

14 Responses to Making tunnels for mason bees

  1. Bruce says:

    Great site. Thanks for the information. Do you refridgerate the cocoons? If so when?

    • Paul B says:

      Hello Bruce,

      I have a dirt-floor cellar which keeps everything chilled between 3° mid-winter and 14° in the Summer and humidity levels are also high >30%. So I don’t refrigerate. I considered it once with our old fridge, but as I cannot control humidity levels, I had concerns the bee cocoons would be dried out as fridges tend to be dry. So I stick with the cellar. What about you?

  2. angela says:

    I refrigerated some cocoons last year and, in April, I put the cocoons in a plastic box in the “attic” of a bee house. All the bees came out. I have three different kinds of bee condos going this year. They are all getting bees. Also, if I move the filled tubes gently, I won’t disrupt the larvae? Should I hold and store the tubes vertically so the larvae fall into the food or always keep the tubes horizontal? Last summer I covered the wooden condos with nylons and stored them in my shed with their tunnels vertical. I did get bees out of them this spring. The cocoons in liners went into the refrigerator in the fall. I love my mason bees but I hate those darn flies! It is very stressful to see them loitering around my bee houses; I kill every one I see. Is there any way to repel them?

    • Paul B says:

      Hello Angela,
      Although the bee larvae appear to be fragile – they don’t react to light and don’t appear to be mobile – they are pretty much stuck to the pollen loaf in their early days. So as long as you do transport the tunnel with care (no shocks, drops or shakes) they should be fine. I actually dropped a reed last year, tagged it up and set it aside but noted on opening it up for disinfection that all the larvae had reached the cocoon phase. I think you just have to avoid dropping a full block when taking it down as the numbers of cells multiply the chances of a larvae or two getting concussed.

      As I’m not known to wear nylons, I generally have to put my nested tunnels away from the walls where chalcid wasps will turn up. I even put them in a spare room in the house so they are not excessively exposed to the sun and where they will lose all the humidity that encourages the development of mites, whilst still benefiting from summer temperatures.

      As for those darn pesky flies, aside from cleaning all your tunnels in the autumn so that you don’t breed and concentrate them in your managed population (the best way), the only one other tip I got from Dave H. @Crownbees was to have a water spray bottle at hand to wet them and stop them flying off in order to squish them more easily. I tried it, but with limited success as the power of the jet I was using was difficult to regulate and tended to make me lose track of them as they were propelled against the brick background. Anyway, I’ll be damned if those pesky flies force me to wear my reading glasses when I am outside, so direct squishing will remain my method.

      • Jeff says:

        Does anyone have advise what to do once the Wasps have invaded my colony?? This is my first year with Mason Bees. I purchased 4 tubes and they filled 32! I was so excited until the Wasps came in mid/late June. I had not read up enough prior to this & was told the bees were done by end of June. By the time I took them in they were getting eaten alive. They are inside in plastic bags but the wasps keep on multiplying. I kill them by smashing but they keep on drilling. Would foil wrapped around remaining tubes work to keep wasps from moving in and out and drilling new holes? I opened a few tubes that had more holes than N. Dakota fracking and indeed the poor Masons were empty nesters :-( I would like to save what is left if that is possible. Any help is appreciated. Next year I will know to bring them inside early June.

        • Paul B says:

          Hi Jeff

          Thanks for your message, I just sent you 4 tips by email as to what you can do to control them once you have suffered an attack. If there’s further requests from others I will put up as a post in the next few days.

          Good luck with managing it!

  3. Just one note of caution – as in natural tunnels, any mason bee cells located paper-straws, cardboard tunnels or reed tunnels will be subject to the attack of Chalcid wasps after the spring.

  4. Denise says:


    I am looking to make these with a group of children. Is there a preference on the type of paper used? Can recycled paper be used to make the tunnels? Or is this paper more susceptible to water issues?

    • Paul B says:

      Hello Denise,
      Thanks for your question – recycled paper is perfect. I have used the brown paper from business envelopes, but you could test out other paper like white printed paper that you might ordinarily recycle – a few white paper straws were adopted when I tried them, but I have not tested preferences for brown versus white, so it might be an interesting experiment with the children. You could also do some maths by saying that the paper needs to be wrapped at least three times around the rod/pencil so it is thick enough, so if they’ve learnt about circles they could calculate the width of the paper needed. I would say that the length of the tunnel needs to be at least 12,5cm or 5 inches. I have tested up to 25cm length straws and the bees like it (just don’t place them in circular crisp tubes as the foil interior makes it too hot for the larvae and creates humidity issues). If you have any more questions don’t hesitate to ask.
      Good luck,

  5. Lewis Bates says:

    In the early part of 2013 I came across this paper tube method. I was enthused and constructed a special sheltered box and placed 150+ tubes in the box and fixed it onto position in a sunny place near an existing successful box. All tubes were made as per the instructions.

    Furthermore I made a further amount and placed them alongside the bamboo canes I had prepared for the coming summer.
    The result was none of the 150 were uses at all.

    Box Number 2
    Of the second box all the bamboo canes were used by many leaf-cutters and masons bees. None of the paper tubes were touched.
    In another case I drilled holes 5 inches long and carefully cleaned the holes and then lined each with parcel paper as above. Only three of the 36 holes were used by leaf-cutters.

    I am puzzled by this result and will not now be using paper tubes again.

  6. Michelle says:

    Hi Paul,
    I live in Denver and after having my mason bee house hanging for 3 years, I finally have some inhabitants. However, I am not sure what they are. From everything I have read, mason bees plug the hole with mud. My holes are plugged with dried pieces of grass. The “bees” did this in August. I could only see the heads poking out of the tubes and could not see their bodies. Do you think I have mason bees or is it possible I have wasps? I don’t want to harm them if they are indeed bees but am also worried if they are not. Thanks!

    • Paul B says:

      Hello Michelle
      It sounds like something similar to the beautiful solitary wasp Mexicana Isodontia – they are an elegant metallic blue-black, nearly an inch long. Like the vast majority of the 100,000 species of wasps, they are perfectly harmless to humans and suffer from the bad name of Yellow Jackets or certain hornets. As I understand it they prey on crickets which when captured, are anaesthetized and eaten alive by the larva whose egg is laid upon them. The grass you see is their nest cell material. It sounds like you left your mason bee house in June/July. In respect of the hotel not otherwise being habited, did you make the hotel or buy it? What do you think the issue could be with it?
      All the best and thanks for asking the question,

  7. Raymond Kilminster says:

    I’ve been rolling my own paper bee tubes . Have cutting up and using the pages of old wildlife magazines ,rolled tight around a pencil I then put the tubes inside a large a very hard cardboard Tube which I get from work . Which come out of our kodak photo printer machine which normally through away . How thick should the paper tubes be I use one A4 size page to make one tube is that to much do you think . I would be grateful for your reply on this point . Many thanks , Raymond , London .

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