I'm new to these solitary bees myself, having just purchased some this winter. A search here didn't turn up a lot of info, so I searched the web and will share what I've found.

Foodwise, they seem pretty easy to please: in addition to the flowers of fruit trees, they particularly like heaths & heathers, eastern redbud, berries, willows, chokecherry, Cranesbill geranium, dandelion, broom, mustards, beard tongue, radish, salvia/sage, dusty miller, white clover, vetch. They're reportedly very fond of borage and pieris japonica (Japanese andromeda). Also like wallflowers, lavender, rose (single varieties are best) forget-me-not, violet, beans & peas, rhododendron, azalea, dill, parsley and carrots.

Some of the above bloom particularly early, like the pieris and some varieties of heath/heather (my two varieties of heaths are just finishing and just starting to bloom now, and pieris will be blooming very soon).

The latest I've heard on placement of the nester is that an east-facing exposure is best, well above the ground, and they don't like dappled shade. A nearby supply of moistened well-sifted soil (I'm told a good clay content is good) for building material will make their job easier.

After the mason bees have finished their activity for the year, you may see other solitary bees using the nester (O. cornifrons and O. coerfulescens, and the leafcutter bee, Megachile spp. Apparently they all get along just fine.

You may want to put something over the front of the nester to exclude predators (like woodpeckers) that will break through the mud-sealed chambers to feed. Some people report wire mesh works.

I'm preparing to put my bees out just jow, in coastal New Jersey, USDA zone 7. We've had alternating warm and cold spells (several days in the 50-60 range, followed by colder spells with nights in the mid-20's), so I kept them in the fridge, but I think it is now reasonably safe to put them out here. You'll want to consider your local weather patterns. They can take the cold, after all, they are native insects, but if hit with frigid temps after they've emerged, or started to emerge, I'm afraid they might be weakened or killed outright.

One website I found helpful is www.pollinatorparadise.com - you'll see articles on Rearing Solitary Bees, FAQ, and A Bee Garden for Attracting Osmia. If I can again locate the others that were particularly useful, I'll post them for you.

I'll sure be glad to see any advice from GardenWeb members who have experience with these bees. In the meantime, though, like you, I'm excited and eager to set them out to do their thing!

Good luck to you!

Diane

Also a newbie, so I don't have much advice! I'll probably put mine out this weekend. Gretzky, what kind of plans did you find for a bee setup? I used some 2x4s this time and will have to trim the paper straws but next year I'd like to make one with deeper holes.

I do know they love Cosmos.