Garden Mastery: San Diego’s native bees, plants are bonded for life

Native bees belong to a group of animals we call pollinators and they play a crucial role in the biodiversity of our plants, flowers, fruits, vegetables, landscapes and crops that sustain our environment and food supply. Other animals that we value as pollinators are non-native bees like the honey bee, beetles, ants, birds, bats and even mice.

Bees are immensely diverse, with an estimated 20,000 species worldwide, of which about 3,600 species are native to North America and 700 species can be found right here in San Diego. Because many native bees have become specialized pollinators of specific native plants, their size and appearance vary widely. North American species range from one-twelfth of an inch to more than 1 inch in length. Their colors also vary in shades from white to black – including red, brown, orange, yellow, blue and even a metallic green.

Mallow, Alcea spp.from the mallow family, attracts pollinators in hardiness zones 4 through 10.

(Jodi Bay)

Almost all types of flowering plants require pollination to produce new seeds and fruit and to maintain their genetics. Animals are more effective than wind when it comes to pollination. Plants attract pollinators by providing food in the form of pollen and nectar, shelter, nest building materials, and a place to find a mate.

The energy that fuels pollinator survival comes from sugars in nectar and the proteins, fats, vitamins and minerals in pollen grains. Native bees exhibit a behavior called “flower persistence,” meaning they repeatedly visit flowers of a particular plant species each time they forage. This makes them effective pollinators, bringing the right pollen to the right sources.

When out and about in San Diego, take the time to observe the many different flower morphologies. You may see the tiny clusters of flowers on a Ceanothus that perfectly match a butterfly’s mouthparts; a cactus flower being visited by a digger bee Diadasia australis, a cactus pollen specialist; or perhaps the very large open petals of a California poppy visited by a greater variety of pollinators. Each of these plants has a specific set of pollinators that can get the job done.

A pollinator visits a sunflower that has heavy, sticky pollen.

Sunflowers have heavy, sticky pollen that needs a pollinator to move it from flower to flower and produce the seeds we use as a snack.

(Jodi Bay)

Bees native to San Diego such as Andrena spharalceae, from the mining bee family, like to nest in sandy soil, another option in your garden for habitat diversity. Mining Bees (Family andrendiae), furrow bees (Halictus spp.) and many others live mostly solitary lives, with a single female doing all the work of building a nest, gathering resources to feed larvae, and laying eggs to start the life cycle over.

Two-thirds of native bee species live in underground nests in complex tunnel systems designed to protect the developing larvae from predators, fungi, weather conditions and other diseases. Other native bee species such as leafcutter bees and mason bees prefer hollow plant stems and above-ground branches to build nests. The female bee creates chambers in the hollow stem to lay her eggs, taking care to line each cell with waxy secretions, leaves or flowers, mud, or chewed wood to protect her young.

Native pollinators at risk

Research shows significant declines in native pollinator populations worldwide. As a result of environmental stressors such as habitat loss, climate change, pests, parasites, pesticide exposure and disease, up to 40 percent of pollinator species are at risk of extinction in the coming years.

A recent analysis by the Xerces Society and the International Union for Conservation of Nature (IUCN) found that 28 percent of bumblebees in Canada, the United States and Mexico fall into an IUCN threatened category. According to NatureServe, 50 percent of leafcutter bee species and 27 percent of mason bee species are “endangered.”

The secret bond of partnership is that neither plant nor pollinator populations can exist in isolation – should one disappear, the other is only a generation away from disaster.

Mimicking the patterns of a honey bee, a hoverfly visits a California poppy, Eschscholzia californica.

Mimicking the patterns of a honey bee, a hoverfly visits a California poppy. Eschscholzia californica.

(Leah Taylor)

Ways to help pollinators

Our native pollinator bees need flowering plants, nesting and wintering sites, and a pesticide-free habitat to survive. Choosing the right plants is an important step in supporting pollinators. Native plants are adapted to our unique soil and local climate, require little to no additional water for maintenance, encourage local biodiversity and are attractive landscape plants. Visit one of the many San Diego nurseries specializing in native plant landscapes to incorporate a variety of native wildflowers, such as these:

  • yarrow
  • Pacific Bleeding Heart
  • California poppy
  • Dwarf Checkerbloom
  • Silver Lupine
  • Mountain Blue Penstemon

… and trees and shrubs:

  • California false indigo tree
  • Palo green
  • Black Sage
  • blueblossom
Carpenter bees love the wide-open flowers of Parkinsonia aculeata, a native Palo Verde tree.

Carpenter bees love the wide open flowers of Parkinsonia aculeataa native Palo Verde tree.

(Leah Taylor)

A small gesture with a big impact is providing bees, butterflies and other pollinators with a source of water, such as a shallow cake pan filled halfway with marbles. The marbles create a landing pad and prevent accidental drowning.

Pesticides – whether organic or conventional – have a huge impact on non-target pests if not used properly. Follow all label directions on all products you use and implement an integrated pest management (IPM) strategy to control target pests while protecting beneficial insects and pollinators in your spaces. Pollinators also need advocates like you to transform their landscapes by creating and maintaining habitats optimized to support pollinators. Visit the resources of the UCCE San Diego Pollinator Project, the Xerces Society, and the California Native Plant Society – San Diego Chapter for more pollinator identification and planting guidance.

Taylor is a California Master Beekeeper and Master Gardener Program Coordinator. For questions about home gardening, contact the UCCE Master Gardeners of San Diego County Hotline at (858) 822-6910 or email

Leave a Comment