Optimal conditions for native bee species are comprised of: 1) abundant forage, 2) minimization of exposure to pesticides, 3) minimization of predation or parasitism; and access to: 4) mating sites, 5) nesting sites, and 6) protected overwintering sites. Some of these factors can be controlled in some locations and some can not. Forage for nectar and pollen is critical for all bees. It has been documented that the greater the diversity of pollen and nectar plants and the greater their local abundance, the greater the native bee diversity and density. This is no different for leafcutting bees. Many of the species in the US are early spring bees and as such require flowering plants from the onset of spring through to the beginning or middle of the summer. Investment in forage can range from periodically mowing fields or habitat borders that undergo succession to planting of specific wild flower mixes or crop plants such as clover, vetch, sunflower, sweet clover, borage, etc. There are several good web sites that suggest appropriate floral mixes for specific geographic locales. Avoid planting of invasive plants! Mason bees use mud for lining nest tunnels. Therefore, areas that have limited bare soil can be enhanced by the clearing small patches of vegetation down to the soil surface. Leafcutting bees line or solely cap their tunnels with cut leaf or petals. Access to flowers with large petals (roses) or soft spring leaves (maple, viburnum) can also help. Leafcutting and mason bees tend to be susceptible to pesticide residues, especially certain insecticide residues. This is especially true since they forage for leaf material. Refrain from applying insecticides liberally, especially those such as carbamate and organophosphate insecticides that are persistent in the environment. Although not a great amount of evidence is available, some scientists hypothesize that systemic insecticides that are taken up by the plant and have the potential to contaminate nectar and pollen can be deadly to bees. Therefore, refrain from blanket use of these insecticides on ornamental plantings that might be an important bee forage plant. Research has been conducted that has shown nest sites can be limiting to populations of leafcutting bees. Maintaining some weak or dead trees in an adjacent woodlot, planting of shrubs with soft interior pithy stems such as elderberry, or construction and deployment of artificial nest sites (nest blocks...see below) can provide nest sites that provide resources for population increase. These are just a few of the practices that can be followed. For more details research bee conservation techniques on the web.

- Frank Drummond, University of Maine

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