Leafcutting and mason bees can be encouraged and raised by following the guidelines above for their conservation and by deploying nest materials in your yard and farm. These bees are very interesting to watch and so in addition to them providing a pollination service, they are also fun to manage. Purchase or construction of nest materials is mentioned above. There are a few points in deploying these nest materials. They can be deployed anywhere with a sunny exposure: on the sides of buildings, fences, on posts in the middle of fields, and along forest of woodlot edges (optimal). When deploying nest materials get them out early, prior to adult emergence. Hang them at least 4 ft above the ground and facing east or south if possible. Position them so that they are hanging slightly down so that rain will not enter the opening and flood them. Leafcutting bees are fairly selective in their choice of micro-habitat, so hang many nests, 30-50 is not too many. In areas that insectivorous birds are populous hang aluminum pie plates that blow in the wind on top of the nests or place the nests in areas that birds are reluctant to perch. This is not always possible and the birds may end up eating only a few bees. Woodpeckers can be quite destructive. It does not take them long to learn that nest blocks harbor bee larvae. One woodpecker can destroy several nest blocks in a day. If this is a problem, wrapping the block in hardware cloth works fairly well. Blocks can be left out over the winter with good results, but they can be taken in and stored in an unheated building and then redeployed in the spring (this also reduces woodpecker problems). Add more nest blocks each spring in areas that have many tunnels capped by leafcutting or mason bees. Inspect to make sure that your occupants are bees (see above). Parasitic wasps will also take advantage of the nest materials and with some success parasitize the bees. More advanced management practices are available for the leafcutting bee enthusiast that can be applied to reduce parasitism, but these practices are beyond our discussion here.
- Frank Drummond, University of Maine
