Any talk about pollinators would not be complete unless I remind you about the importance of pollinators in our lives. One in three bites of food we eat is made possible by pollination. Seventy five percent of the worlds’ flowering plants and over a third of the world’s crop depends on pollination. The crop pollinators contribute more than 24 billion dollars to the US economy, benefits from native insect pollination in the United States were valued at more than 9 billion dollars.
Why are we worried about pollinators? You may be aware of the problems that have begun to confront the honey bee industry with colony collapse syndrome and loss of bee hives (2006). Honey bees are declining 44% annually. With these concerns the industry began looking at native bees to fill a future gap in pollination services. Honey bees came to North America in 1622 with the first settlers from Europe. Of course, prior to the arrival of the honey bees, native bees were providing pollination services. With the closer look at native bees, other challenges facing pollinators were highlighted: loss of habitat, an abundance of non-native plants, invasive species of plants, and pesticides. Because of habitat fragmentation the idea of hedgerows or plant corridors has emerged. Our back yard gardens or hedgerows along fields will help provide wildlife corridors.
Who are these pollinators? Pollinators are bees, wasps, butterflies, moths, hummingbirds, beetles, flies, and bats. I am going to focus on three main groups: Bees, butterflies, and hummingbirds. We will look at the needs of each of these groups so we can plant a garden for them to thrive. All need food (pollen and nectar), water and shelter.
Bees
Bees are the most prominent group of pollinators. People are most aware of honey bees and honey bees are what you might call generalists. They can utilize many different flowers and of course we can support them with nectar and pollen. Native bees tend to be more specialists and utilize the native plants with which they have evolved. There are 4000 native bee species in North America, 1600 in California, 300 bee species in Yolo County, 60 species of which visit crops. At Honey Bee Haven on Davis campus 80 species of native bees have been identified.
Social Bees and Solitary Bees. Honey bees are social bees. Social bees live and work together in a hive over several generations. Bumble bees and some sweat bees are natives that are also social bees. Most native bees are solitary bees. Solitary bees provision their nest and lay their eggs for the next generation on their own—no hive and no honey. Seventy percent of native bees are ground dwelling bees and the remainder are cavity dwellers.
Cavity dwelling bees use hollow stems of pithy plants, tunnels left by wood boring beetles, crevices, and in the bee houses that you may have seen. Mason bees, leafcutter bees and carpenter bees are cavity dwelling bees. Mason bees and leafcutter bees look for tunnel-like spaces for their eggs. Once the female bee mates, she begins to look for a place for her eggs, a tunnel in a reed or crevice or your bee house, then she begins to gather pollen (protein) and nectar (carbohydrate) and provision the nest at the end of the tunnel. Then she will back down the tunnel and deposit an egg. In the case of the Mason bee, she will bring mud in and seal the small cell with the egg. She will continue to fill the tunnel with cells. As she places the egg she can chose to fertilize it and the bee will be a female or chose to have the bee be a male. She will usually place the females in the back and place the males in the front. There the egg will become a pupa and then a fully formed bee will emerge the next spring. The males in the front will be waiting for the females and the cycle will begin again. The leaf cutter uses leaves instead of mud to partition the egg cells.
Ground dwelling bees include mining bees (Andrena) alkali sweat bees, polyester bees (Colletes), and Squash bees.
Bees prefer blue, purple, and yellow flower with a sweet scent. Bees cannot detect the color red. Bees can work more efficiently when they can work several of the same flowers grouped together in drifts of blooms approximately four feet. Try to have some plants in bloom in each season.
For example:
- Winter and Spring: Ceanothus, Western red bud, rosemary
- Summer: Asters, California Goldenrod, Gallardia (blanket flower)
- Fall: Salvia greggii (autumn sage), Eriogonum fasciculatum (California buckwheat), Sedum Autumn Joy
For information of California native plants go to Calscape.
Butterflies. There are over 700 species of butterflies in the United States belonging to six different families. Butterflies occur in all 50 states. There are 38 species of butterflies regularly found in Yolo County and 11 others occasionally. There are 65 species of butterflies regularly found in Solano County and one other occasionally. The best reference for Butterflies in our area is Dr. Shapiro's Butterfly website.
For butterflies, you have to think of two types of plants: Host plants and nectar plants. Host plants are the plants on which butterflies choose to lay their eggs because their larva (caterpillars) can only eat a specific plant. Depending on the species, some caterpillars are generalists (more that one host plant) or specialists (only one host plant). Adult butterflies may be attracted to entirely different plants for nectar and they may be more generalists in this choice. Examples of specialists include: Monarch-milkweed, Dutchman’s pipe vine: Pipevine swallow tail, Passion vine: Gulf Fritillary.
Butterflies favorite colors are pink, purple, yellow and orange. Flat flowers (zinnias, cosmos), short tubular flowers (lupine) and flower clusters (verbena and lantana) are best as they provide and landing spot for easy access to nectar. Drooping flowers do not provide a place for the butterflies to perch to sip nectar.
Basking: Since butterflies are cold blooded they need to warm up in the sun for their flight muscles to work. A sunny spot on a flat rocks in a wind protected spot can be provided.
Puddling: Mostly male Butterflies gather around puddles to sip water with salt and nutrients. They visit puddling sites during the heat of the day, typically between 10 a.m. and 2 p.m. Puddling nutrients also help the males to produce pheromone, the chemical that males release to attract females. You can entice more butterflies to visit your backyard by adding a puddling area in the flower garden.
How do butterflies survive the winter? Most butterflies overwinter as eggs, caterpillars or pupae depending on the species, but the Mourning cloak, Milbert’s tortoiseshell, and Angle-wing butterflies spend the winter as adults. In your garden, tree cavities, leaf litter and branch piles shelter over-wintering butterflies from predators and cold weather.
“Most species enter a dormant phase. This can be as an egg, larva, pupa or adult insect, dependent upon species. The majority of butterflies and moths overwinter in the larval stage, with pupae being the next most common choice, followed by eggs and adults. A few are capable of overwintering in more than one stage.” https://butterfly-conservation.org/3114-3219/heating-and-hibernation.htmlhttps://butterfly-conservation.org/3114-3219/heating-and-hibernation.html
Hummingbirds There are 325-350 species of hummingbirds in the world located only in the Americas. There are 16 species in the US and Canada, and 8 in California. More than 160 North American plants depend exclusively on hummingbirds for pollination. The Anna’s hummingbird lives in our area year-round. We need to provide nectar and shelter throughout the seasons. Other hummingbirds pass through on their migration and some may travel 600 miles at 25 MPH, journeying 3000 miles a year.
Hummingbirds don’t have a good sense of smell, so hummingbird flowers are often unscented. But they see color just as well as humans. In fact, they can also see ultraviolet light, which means their world appears even more colorful than ours. They look for brightly colored tubular shaped flowers for nectar. Hummingbirds also eat small insects and other arthropods caught in flight or from vegetation. Nesting material are bound together with spider’s webs, downy feathers, plant fibers and hairs and covered with lichen. (1 1/2 to 2 inches in diameter) The incubation period typically ranges from 14 to 19 days in length, and they may leave the nest in three weeks. Wings flaps 12 to 90 times per second depending on species.
How to start a pollinator garden
Location:
First you need to select a place for your garden. A sunny location where you can find soil. If you don’t have a good spot in the ground, you can create a raised garden or use containers. Avoid an area that gets lots of heavy wind, a more protected or sheltered area would be best. You need a location that gets at least six hours of full sun.
Plant Selection:
For plant selection, you want to think about the requirements mentioned for pollinators. There are many lists of plants available to help you in your choices. There is a list on the Haagen-Dazs Honey Bee Haven website under resources. The bloom time is noted and whether the plants or flowers provide honey, pollen or propolis (see below). Flowers in bloom throughout the year is important for our Anne’s hummingbirds and butterflies that overwinter. This list is focused on bees but many of these plants are attractive to other pollinators: butterflies, hummingbirds, moths, beetles, wasps, and beneficial flies.
Native plants:
Native plants evolved with native creatures and are suited to their needs. Native plants are four times more attractive to native bees than exotic flowers. Native plants are indicated with an asterisk on the bee haven list. UCCE Master Gardeners website under Free Garden Pubs and Pest Notes has other lists of native plants and well as the CNPS (California Native Plant Society) website. UC Arboretum website is also a source for pollinator friendly plants.
Avoid hybrids:
Avoid modern hybrids especially the double flower forms, as they are bred varieties that look and smell pleasant for humans but aren’t always accessible for nectar or pollen for bees.
Blooms available in all seasons: Select a variety of plants that will allow for blooms throughout the seasons. Shrubs and trees tend to bloom early in the season and will provide a source of pollen and nectar when other sources are scarce. The bee haven list includes the bloom times for each plant. Flowers in bloom throughout the year is important for our Anne’s hummingbirds and Butterflies that over winter.
Floral Rewards:
Pollen for Protein and Nectar for carbohydrate. OILS AND RESINS are secreted by some flowers to attract bees. Extrafloral nectaries and honeydew.
Bee preferences:
Most bees are oblivious to the color red. Pale to dark shade of purple and blue or white with violet markings (nectar guides) attract bees. Contrasting patterns of flower shades, tints, and tones further direct pollinators toward floral rewards such as nectar or pollen, much like the nighttime runway lights of an airport. Bees are also attracted to white, yellow, orange or pale to bright pink flowers as well. Bees are drawn to sweetly aromatic or minty scented blossoms.
Drifts:
Plant in patches or drifts of the same flowers. This allows for better foraging efficiency.
Water:
Provide a source of water. Bees need something to perch on such as rocks or corks.
Bare ground:
As already mentioned, most of the solitary bees are ground nesting bees. Females excavate a nest in dry soil and mound the loose soil around the nest entrance. The area needs to be free of mulch to find their homes. Bare ground, some like sloping ground some like flat ground is needed. A southern exposure for full sunlight. Nesting activity is limited to spring. One article suggested planter with soil
(Ground-nesting bees include the digger bees (family Anthoporidae), sweat bees (family Halictidae), and mining bees (family Andrenidae).)
No Pesticides
Mud:
Female mason bees need mud to make the partitions to seal off the egg chambers, another reason to have bare ground without grass nearby. The mud needs to be moist but not soupy. Make sure the muddy area is not directly below the bee box because the newly emerged bees are weak and we don’t want them to fall in the mud. Butterflies can use a moist area for puddling.
Nesting Materials:
Provide nesting sites for wood-boring bees with dead trees, snags or fallen logs. Minimize pruning of pithy shrubs such as elderberry, sumac or hydrangea for year to year. Consider providing a bee box. Plants also offer nesting, egg-laying, and overwintering resources for pollinators, such as hollow or pithy canes; stalks, stems, or twigs; leaves, petals, or plant fibers; and exfoliating or peeling bark.
Propolis:
Honey bees collect propolis to construct and defend hives, weatherproof small cracks and holes, smooth surfaces, dampen vibrations, and protect themselves from bacteria, fungi, mites, and other intruders. Species of solitary mason bees also collect propolis to construct, partition, and seal nests.