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Beneficial Insects


San Francisco Bay Region Native Plant Species
Supporting the Greatest Diversity of Native Bees

compiled by Jeffrey A. Caldwell


There's a lot of concern about pollinators now, since they seem to be disappearing ... humanity has not been managing the world for their benefit, by and large, though their work is of very great benefit to humanity.
Many of the hardest working or most effective pollinators are native bees ... bumblebees, sweat bees, leafcutter bees, carpenter bees, digger bees, etc. -- a huge variety, mostly little known to other than entomologists, many small and mostly docile.
Attached are documents about the locally native plants from which the greatest diversity of bee species have been collected ...
The increasingly shrinking pollinator-effective populations of these plants no doubt is a major factor in pollinator decline locally.
Minimum suggested patch size per species: 25 square feet, bigger is better ­ especially to make commuting worthwhile for social bees, and simply to have enough color and fragrance for more insects to find the resource and sufficient provisions to survive after finding it. I suggest at least 100 square feet as minimum patch size for goldfields and tidy-tips. To produce a maximum amount of nectar and pollen the plants must be healthy and not under drought-stress.
The number for each plant species is the number of bee species collected from it, wherever the plant occurred in whatever community the bee diversity was greatest for it, namely (in cases where the plant occurs in more than one community) in the community where the plants receive the most sun. Number of species data gathered from: Andrew R. Moldenke's 1971 Studies on the Species Diversity of California Plant Communities, a Stanford University Ph.D. thesis. Flowering times are from Flora of the Santa Cruz Mountains of California by John Hunter Thomas.
Suggesting "suites" of species for effective habitat gardens is a favorite idea of Andreas Reimann, co-author of The California Landscape Garden: Ecology, Culture, and Design. Each suite is designed to provide nectar and pollen from early spring to late fall, with overlapping flowering to heat up pollinator interest.
Any of these combinations will attract and help support plenty of other insects and wildlife besides bees.

For additional information on garden and landscape design and management for native bees see:

Urban Bee Gardens

Xerces Society Guidelines

      NOTE: Ten or more bee species collected from the flowers on these plants

   Data from A.R. Moldenke, 1971, Studies on the Species Diversity of California Plant Communities, Ph. D. Thesis, Stanford University, 355 pages):

Western Horticulture Society
PO Box 166, Mountain View, CA 94042