A pollinator garden's diverse plants and colorful blooms attract and help to support a variety of birds, butterflies, moths, and beneficial insects year-round. These visitors play a critical role in sustaining our ecosystem by helping our plants reproduce. Pollinator gardens provide the habitat, plants, pollen, and nectar to help us care for our wildlife partners. Transfer of pollen is the plant's goal, and nectar and pollen are the pollinator's reward. Flora and fauna evolve together in interrelationship. A pollinator garden can provide the habitat and food those pollinators need and give much personal satisfaction in the process.
All living things on the earth need food, shelter, and/or oxygen that the plants provide. Plant reproduction is crucial to the continuation of this cycle. Plants are more than willing to participate in this cycle but they can't move and, in many cases, may need a little outside help to reproduce. Enter the pollinators. Plants have developed rewards and lures in the form of attractive scent, color and nectar to draw pollinators. The pollinator visits the flower lured by these encouragements and in doing so brushes against the plant's pollen producer, dusting the pollinator's body with that pollen. When the pollinator moves on to the next plant, the pollen carried on their body is distributed to that next flower and, viola, that plant has been pollinated.
Bees are perhaps the first thing people think of when pollinators are mentioned, and honey bees the first bee most people will think of. But there is more to the story than that. Here is a list of some of the many bees that pollinate our plants:
Honey Bees Apis mellifera
Honey bees are hardworking but non-native pollinators.They are not as effective at pollinating as most native pollinators.They are subject to numerous diseases and pesticides, making colonies fragile. Maintaining colonies is expensive and time consuming.
Native Bees
There are 450 species of bumble bees in the world, 40 species in North America, and 26 of these species can be found in California. Encouraging native bees, the ones already living in the neighborhood and working, is good pollination planning. The native bees are more efficient than the imported bees because these bees evolved alongside the native flora and their peak activity will coincide with the bloom cycles of the native plants. Some have adapted to pollinate specific types of plants or even particular plant species. Most native bees are solitary instead of living in hives, though they may nest in communities where the food is plentiful. They work individually sharing a common resource. Native bees are themselves food for the native wildlife and because they don't have a hive to protect, they rarely sting potential predators (including humans).
California Bumble Bee Bombus californicus
This bee is an important pollinator of agricultural crops. It is social with queens and workers that nest underground and form new colonies each year. It is black and yellow, large and hairy and was once the most common bumble bee in California, but its numbers have declined in recent years. Possible causes of this decline are the use of pesticides, invasive species and importing commercial bees.
These bees, with their thick hairy coats, are the powerhouses of the bee family working in rain, sleet and wind. They can be found clinging onto flowers in gale-force winds and struggling through early snows to bring home the nectar. Native solitary bees are in the following categories: ground nesters, leafcutters, cavity nesters and masons.
California Digger Bee Anthophora californica
These bees look like bumble bees and are known for constructing nests beneath the soil. They are not aggressive and are mostly solitary, though the females do construct their nests in groups, sometimes in the hundreds . They are important because they pollinate some of the plants that are not often visited by honey bees. Make sure to have areas of bare soil available in your garden and watch where you walk to not trample their holes.
California Carpenter Bees Xylocopa californica and Xylocopa varipuncta
These bees are some of the largest native bees in the United States. They are gentle giants and get their name from their excavating nesting habit. They tunnel into wood forming galleries to lay their eggs in. They are long lived and social. Carpenter bees forage on multiple types of plants. When they land on a plant, they use their ‘humming' to move the pollen out of the plant via sound waves. This is called buzz pollination.
Since these bees are so large and are unable to fit into flowers with small openings like salvias, they have developed a neat trick to get at their reward. To reach the nectar/pollen they will cut a slit at the base of the flower and steal their reward. This method is only used on plants with small flower openings and does not pollinate the flower.
Wool Carder Bee Anthidium maculosum
These bees are solitary and carry their pollen in structure at the base of their abdomen (called a scopa) instead of carrying pollen on their hind legs. They get their name from the female's interesting habit of scraping off hair from fuzzy leaves and stems to build their nests.
The wool carder bees nest in pre-existing cavities. In the garden, these can be in cracks in walls or buildings, knot holes, old leftover borer holes in wood as well as openings in branches and twigs.
The males are aggressive in protecting their territory and will ‘dive bomb' other bees away from their chosen plants. They have the nickname "bossy bee" or "bully bee".
There are around 350,000 pollinator species in the world. Though they are the most recognizable, bees are not the only plant pollinator team in town. Other insects help carry this responsibility. Butterflies, flies, moths, beetles help with pollinating plants and birds, bats and other small mammals and lizards fill out the plant pollinator roster as well.
And finally, please avoid pesticide use as much as possible in your garden because it is indiscriminate and will kill these wonderful pollinating insects along with the pests. Consider instead, using some IPM-Integrated Pest Management methods as outlined at UC IPM .
Information links:
UC Davis arboretum native bee info
Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143. Volunteers will get back to you after they research answers to your questions.
Visit our website: napamg.ucanr.edu to find answers to all of your horticultural questions.