I have extensively read this forum searching for which plants would be best to use for nesting material for leafcutter/mason bees but have only come across a reference to giant parsely and reeds. Which plants are used for this nesting material as I would like to acquire some.

I have noticed 40-60 female leafcutters visiting my woodpile so I made 6 nesting blocks (5/16" dados for tunnels) and none of the girls seem to want to visit the blocks. I have the blocks covered with some aged firewood for protection from the elements but I have not had one taker in over a week. There are three 40 acre plots of alfalfa within 500-600 feet of my woodpile so I was wondering what an optimal location would be for the blocks (closer to the fields) or possibly try to cover the woodpile so the blocks become more appealing?

My main interests are what plants can be used for nesting material and where the best placement would be for the blocks.