Garden Bee-hotels

30th April 2015

In 2012, I started my first experiments with a garden "bee-hotel". Here's the photograph of the newly-constructed hotel as it appeared in the 2012 blog entry; just completed and still awaiting its first Warwickshire residents.

The bee-hotel's first year was not too successful, but successive years yielded higher levels of occupancy and by the end of summer 2014, there had been considerable activity and virtually all the holes were filled. Since then we've relocated to Staffordshire and brought the bee-hotel with us; crammed with bees and no doubt, their accompanying parasites and "hangers-on".

We now have a much larger garden and it was an opportunity to increase the hymenopteran housing scheme as well. Last year there was lots of activity from interesting little solitary wasps as well as bees. I hoped to be able to continue that this year and perhaps increase activity.

I just cobbled together a wooden box with a cut paving slab for a roof (image left). Not as "elegant" as my original bee-hotel, but I'm sure the occupants won't bee too worried. I put all but one of the completed drilled blocks, canes and paper tubes from 2014 into this and then filled the gaps with more drilled blocks, logs and cut plant stems. As before, I included a range of drilled hole sizes from 2mm up to 10mm and used both narrow and wider-stemmed plant material. Hopefully this will continued to attract a range of bee and wasp species.

My "original" bee-hotel has now been filled with newly-drilled wooden blocks. The blocks are 3 inches (~75mm) square and 6 inches (150mm) long. Again, the drilled holes range from 2mm to 10mm in diameter. I drilled the holes as deeply as I could, without going right through the block. Obviously, the smaller holes are much less deep, as the drill bits are much shorter.

The block at the bottom is a 2014 one, filled with Red Mason Bee (Osmia bicornis) nests. The block has 7-8mm holes, which this species seems to prefer. Red Mason Bees are the species most easily attracted to bee-hotels in the UK.

This is my first Staffordshire Red Mason Bee. He appeared on the garden fence on 9th April. I had noticed holes in the openings to a couple of nests in the bee-hotel, so was expecting to see some males around. When female solitary bee start their nest holes, they lay fertilised eggs first, in the deeper brood cells. These will develop into females. For the brood cells nearest the entrance, they lay non-fertilised eggs. These produce males. Males are therefore the first to emerge from the nests. They spend their time flying around the nest holes, investigating anything that moves and waiting for the females to emerge. Their sole role is to mate with newly-emerged females. They then die off and leave the females to the exhausting task of nest building.

Since then, more and more males have been emerging. On sunny days, many dozens are swarming around the bee hotels and nectaring on garden flowers. Females generally emerge much later than males in this species, and I have only seen one up to now, the female on the left which I photographed on 10th April. Females are slightly larger than the males; lack the white facial hairs, but do have two small "horns" on the front of the face. They utilise these when they form the mud partitions between the brood cells. No doubt more females will be emerging soon. I'll produce another blog post when nesting activity starts.

Last year, I also had a few nests completed by the less-common mason bees Osmia caerulescens and Osmia leaiana. Active around the bee-hotels at the moment (in addition to the Osmia bicornis males) are these darker males with a more metallic and bronzey look. They are generally a little smaller on average than the Osmia bicornis too. Although females of Osmia caerulescens and Osmia leaiana are easy to tell apart, the males are much more difficult (I'm not going to try!). Again, in the next bee-hotel update, I'll hopefully have some images of the females. I'll also be able to report on a drilled tree stump that I've prepared in the garden.

[Click on any small image for a larger version]


Photo comment By Mikkel: I'm considering doing something similar to your hotel. However I see that some people advising against using drilled holes in solid wood due to parasites. What are your experiences with parasites? Do the bees use the same holes several years running?
Photo comment By Ed Phillips: Hi Mikkel Most years I do notice some bees carrying mites, but don't know whether this is necessarily due to drilled holes. It could be though. Bees emerging from the bee-hotel will re-use holes, often cleaning out previous nest debris before they do. What I did this year, was to make new drilled blocks and distribute the old ones at different places around the garden after the bees started emerging. It could be that concentrating so many nesting facilities in one place, could cause problems with mites etc. As far a brood parasites such as cuckoo bees and wasps are concerned, I suspect that bee-hotels generally, may make it easier for them to find host nests. I'm not too worried about that personally. I'm not rearing bees to assist in orchard pollination or anything like that. The parasitic species are just as interesting as the host species! Good luck. Let me know how you get on!

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