Terry,
 
    Yes, there are designs of nest structures available.  My reference
    material is rather limited but perhaps Chris Plowright at U. of Ottawa
    can provide more uptodate info.  Also, Phil Torchio at U. of Utah may
    have quite a bit of info available of nest designs for non-Apis
    pollinators (not limited to bumbles).
 
    In addition to the actual placement of 'bait' nesting sites, undisturbed
    vegetation surrounding cranberry fields are equally valuable.  Flooding,
    use of pesticides, clearing of vegetation, and other disruptive
    activities have been the primary causes for the quantitative decline and
    diversity of wild bee species.
 
    Paul van Westendorp                         [log in to unmask]
    Provincial Apiarist
    British Columbia