Masonry Bees

[masochists-r-us]

Masonry bees seem to be multiplying in number every year. There are already so many of them again this year and they're doing a lot of damage. We will eventually get to re-point the rear of our house, but are thinking of putting up something like this in the interim. Has anyone tried them ? Do they work ?

 

[malcolm]

They work well for solitary bees. I've got some and they are well utilised. Noticed 2 bee sized holes in my new pointing so the stubborn might still dig their own holes.

 

[Flyfisher]

We have a few of those ‘hotels’ dotted around the place and they seem to attract some critters though they are not fully occupied.

Some SPAB advice on masonry bees here: https://www.spab.org.uk/advice/masonry-bees

 

[george2019]

Masonry bees seem to be multiplying in number every year. There are already so many of them again this year and they're doing a lot of damage. We will eventually get to re-point the rear of our house, but are thinking of putting up something like this in the interim. Has anyone tried them ? Do they work ?
bee hotel.JPG

What damage are they causing? Pest controllers are keen on getting rid of them but the SPAB is more circumspect: https://www.spab.org.uk/advice/masonry-bees

I think a thousand have been going to work on my south facing wall for a hundred years and there isn't much sign of damage, I had a scaffold against it recently and while I'm sure they've burrowed out, it wasn't critical as 95% of the pointing was sound as per rest of house. I would like to trial a lime grout as if they have created a network of tunnels, it should flow nicely in.

As for the bee hotel I doubt it'd attract them as they like the lime as well as the shelter (I think).

 

[Matt Green]

Pest controllers are keen on getting rid of them

No they aren't, they are impelled to do so by customers. They would be much happier to with pest insects that are significantly less grief.

 

[shobo]

I think I have had some in the front elevation of my hamstone cottage. Either bees or some other reprehensible little so and sos. I'm having to repoint anyway, so I'm not too cross, but if I wasn't repointing this summer anyway, I might spray down the holes / gaps with insecticide, have you considered doing that ?

 

[malcolm]

if I wasn't repointing this summer anyway, I might spray down the holes / gaps with insecticide, have you considered doing that ?

No - bees are lovely! Also they are having a hard time with insecticides at the moment so it's nice to offer them a safe place. They tend to keep themselves to themselves and you can work around them - I once re-pointed a chimney home to chimney bees and found them good company. I left their holes open and repointed/replaced bricks in the rest of the chimney while they went about their business. They lasted a couple more seasons but I've not seen them recently.

The honey bees in the shed were a one season only thing, the burrowing bees didn't plan their flood defences well, so I'm left with the solitary bees this year.

Love your bees! The masonry bees might make a few little holes your building can wear with pride. A network of tunnels would be odd unless you have the little bumble bees (chimney bees) rather than the solitary bees that normally make holes in walls. In any case always repointing is for some other reason. Enjoy the wonderful little critters!

 

[Feltwell]

No - bees are lovely! Also they are having a hard time with insecticides at the moment so it's nice to offer them a safe place. They tend to keep themselves to themselves and you can work around them.

I couldn't agree more! I had white-tailed bumblebees who made their home in a hole in my bay window - they'd got into a void in the roof space. I was renovating the window at the time, they were quite happy buzzing past me as I worked, totally ignored me. They made no mess and completed their life cycle after about 8 weeks - the type of bee I had doesn't return to the same site, so I blocked the hole up after they'd gone. There are a huge number of different types of bee, they need our support to survive.

 

[george2019]

Pest controllers are keen on getting rid of them

No they aren't, they are impelled to do so by customers. They would be much happier to with pest insects that are significantly less grief.

Depends on their scruples! But they are the only people who would benefit from masonry bee removal.

I completely agree with leaving them alone as I've no concerns over them on the wall so long as pointing and brickwork is generally sound.

 

[masochists-r-us]

SPAB recommends you keep up with your re-pointing to deal best with these critters, but we just have so many other jobs to do first, it might be a while. Definitely not planning to use any insecticide, but would like to live more harmoniously with our bee friends!
Anyway, I bought 2 of these things which are very well made, great value at £15 each and they are working a treat. As you can see from the blocked up holes, they're now at least 50% occupied, but we found that they only really work on a south facing wall. Anyway, has definitely resolved our problem,although we may end up having to buy a couple more.

 

[CliffordPope]

I completely agree with leaving them alone as I've no concerns over them on the wall so long as pointing and brickwork is generally sound.

Isn't a purpose of pointing to stop rain getting in?

 

[Feltwell]

Anyway, I bought 2 of these things which are very well made, great value at £15 each and they are working a treat.

Where did they come from? I quite like those.

 

[masochists-r-us]

Got them on line from Garden Wildlife Direct

 

[LeeL82]

So we've been watching the mason bees on the side of the house and the numbers seem to be getting out of control, this little bit on the side of the house which what id consider to be the quieter section as the bits up by the roof there's literally swarms during the day intrigued me last night since there's a lot of sandstone dust on the ground around the area, I managed to dig it out with a pencil the sandstone now that brittle and soft, now I'm worried for the rest of the side of the house, any advice or am I being dramatic?

I thought they were meant to be solitary?

 

[TheForge]

That’s pretty dramatic, but I suspect the cement pointing is the cause of your problems, the masonry bees are just taking advantage of decaying sandstone, obliterated by the moisture trapped in it by the cement and the action of freeze/thaw.

I would look at removing the cement then repointing in lime once the bees have gone in the early autumn.

 

[LeeL82]

That’s pretty dramatic, but I suspect the cement pointing is the cause of your problems, the masonry bees are just taking advantage of decaying sandstone, obliterated by the moisture trapped in it by the cement and the action of freeze/thaw.

I would look at removing the cement then repointing in lime once the bees have gone in the early autumn.

I was thinking that! Trapped moisture luckily the cement is just a very thin layer that looks like it was brushed on! shouldn't be a hard job, just time-consuming!

 

[CliffordPope]

We have an old cottage with walls about three feet thick made of rough stones of various sizes set in a sort of dried mud mortar. The outside wall facing north is pointed with the mud, with later areas patched up with old lime mortar, a sort of crumbly white plaster, and modern cement mortar. The whole lot is painted with a thick slurry of lime. It's not feasible to re-point any other than damaged sections, as the stones start falling out.

There are a lot of holes, about 1/4" across, some of which seem to wind right through the wall between the stones. At this time of year we get lots of very small thin stripey bees (wasps?) appearing inside.
I'm not certain the same species is responsible inside and out, as I've never seen one of the diggers outside, but the inside ones must get in somewhere,in quite large numbers. So far I just patch up the holes, but they still dig fresh ones and get inside.

When rain runs down the wall in winter the water must soak into the dried mud, causing damp to become trapped in the wall and the "mortar" to loosen and fall out.
I'd like to believe the insects are harmless, but I'm not so sure.

 

[LeeL82]

At this time of year we get lots of very small thin stripey bees (wasps?) appearing inside.
I'm not certain the same species is responsible inside and out, as I've never seen one of the diggers outside, but the inside ones must get in somewhere,in quite large numbers. So far I just patch up the holes, but they still dig fresh ones and get inside.

When rain runs down the wall in winter the water must soak into the dried mud, causing damp to become trapped in the wall and the "mortar" to loosen and fall out.
I'd like to believe the insects are harmless, but I'm not so sure.

Ours almost look wasp-like too, I'm told by the neighbour next door they're mason bees.

I started removing the cement mortar, I started on the east-facing wall first where there's no 'bee' damage. and it came away fine, the cemented as though doesn't go deep into the crevices and I've no idea at all why it was ever applied.

The south-facing limestone wall though is a whole other story, removing the cement the sandstone is severely decayed were the bees have taken advantage and just clumps out, I think I'm going to have to look at perhaps lime roughcasting/harling.

pictures attached.

Ideas/thoughts are appreciated.

 

[malcolm]

Mason bees or solitary bees do look wasp like. They will drill a straight hole, or more often take advantage of an existing hole, and lay baby bees. The holes are filled in by something that looks like a wood pulp and the baby bee eats it's way out in the spring. The wood things with holes that I bought for them have proved to be very popular.

Yours looks more like a colony. You may have once had tree bumblebees like the ones I care for in my chimney, or maybe even honey bees that gave my shed some life.

Either way the fix has to be to stop the walls being soft and wet. Rid the walls of that cement and let them dry out. It is hardly a structural issue at the moment and cosmetic repairs will surely be possible on the occasional block that has been damaged by bees.

 

[LeeL82]

Mason bees or solitary bees do look wasp like. They will drill a straight hole, or more often take advantage of an existing hole, and lay baby bees. The holes are filled in by something that looks like a wood pulp and the baby bee eats it's way out in the spring. The wood things with holes that I bought for them have proved to be very popular.

Yours looks more like a colony. You may have once had tree bumblebees like the ones I care for in my chimney, or maybe even honey bees that gave my shed some life.

Either way the fix has to be to stop the walls being soft and wet. Rid the walls of that cement and let them dry out. It is hardly a structural issue at the moment and cosmetic repairs will surely be possible on the occasional block that has been damaged by bees.

Thanks Malcom. Will the sandstone harden again and stop being so crumbly once cement is removed?