Bee habitat is not just flowers, it is also brood space and shelter. Most bees are not honey bees or bumble bees, they are little solitary bees and they do a lot of polination. We need to provide them with lots of brood space and overnight shelter too! And modern garden practice is simply not doing it. First of all, I am not a bee racist. I am trying to help all the bee species. I find that there is a succession of different bee species through the year. And they use different size holes . In fact they don't just lay eggs in these holes, they shelter in them too. I did not know this.. This year I also discovered that they burrow into the pith in old raspberry stems and in grape vines! So if you compost your old raspberry canes, you are probably composting bee babies too. Dave from Camas, Washington has been bundling teasel stems for several years for orchard mason bees. You could do the same with raspberry canes!? http://www.permies.com/permaculture-forums/520_0/critter-care/orachard-mason-bees I found this a week ago after I had started my project. I make holes in cop blocks for the bees. I have also started layering plant stems At least 4 bee species are using the first cob bee blocks for brood or shelter. I have some pictures at the link below. Hopefully you can see the captions too. Brian https://www.facebook.com/album.php?aid=246092&id;=736625766&l;=26546198d6 I am too Lazy to post an instructable right now and I am still learning the cob bee house thing.