CORVALLIS, Ore. – Home gardeners can enhance habitat for native pollinators and lure them to the garden with plants whose color and shape attract bees, butterflies and birds.
"Farmers share the same intent," according to Gail Langellotto, Oregon State University horticulturist and statewide coordinator of the Master Gardener program.
"The importance of bees, butterflies, hummingbirds, moths and other pollinators has become more prominent as honey bee hives are affected by ‘colony collapse disorder’ and other ailments,” Langellotto said. “Pollinating insects and birds are vital players in sustaining plant growth on earth, and with about 19,200 species, the bee is the most important pollinator.”
"The entire body of this tiny buzzing sensation is designed to pollinate. Body hairs and back-leg baskets carry pollen from male to female flower parts. With long-tongued species and short-tongued species, bees gather sweet nectar from both tubular and ray-like flowers to renew their energy. Even the bee's buzz helps pollinate; it agitates flowers to release their pollen through a process called sonication."
Native bees – including bumble bees, sweat bees, alkali bees and digger bees – are not the same as docile honey bees, native to Europe, that live in hives and help produce large amounts of honey. Some native bees live only a year or less, either alone or in small groups, on the ground in hollow cavities in piles of sticks and twigs. Unlike the honey bee, many do not fly great distances and need forage nearby.
"Good nesting sites for native bees are not necessarily the most attractive to the gardener," Langellotto said. "But it's inexpensive and easy to build nesting areas. Bamboo or twigs can be bundled and tied to the trunks of trees to attract cavity-nesting bees. Bare spots in the lawn or garden may attract soil-nesting species."
Bees need both pollen and nectar to survive, and most plants have both. Pollen not only fertilizes female flower parts, necessary for many plants to produce fruit and vegetables, but provides protein for the bee. Nectar is sucrose, a sugar solution that helps power flight.
"Pollinators often choose the most rewarding flowers, and you can help direct them to your cucumbers and squash by growing their favorite flowers nearby," Langellotto said. Bees prefer flowers that are blue, purple, white or yellow. Hummingbirds tend to like red flowers with long, tubular shapes such as the scarlet (or skyrocket) gilia; most commercial hummingbird feeders are aptly shaped and colored. Red and orange flowers also attract butterflies. Moths, many of which fly at night, are attracted to pale flowers that reflect the moon. Flowers that are single petaled provide easy access to their pollen and nectar.
"It's important to have flowers in bloom throughout the season," Langellotto said, "and especially early in the season. Native bees that emerge and fly in early spring don’t have the cornucopia of flowering plants that mid-summer bees can access. Gardeners can help these early-season bees by growing Mahonias or Barberries, native early-season flowering plants that are attractive to bees. Native willows are another good choice."
It's also good to grow flowers in bunches. "Clumped plantings appear to be more attractive to pollinators than individual flowers that are randomly dispersed," Langellotto said.
Bees can fall victim to both pesticides and herbicides, and Langellotto recommends reducing or eliminating their use.
The following are some of the many plants that attract native pollinators and other beneficial insects. Flowers: asters, alyssum, baby blue eyes, basil, cilantro, cosmos, crimson clover, fuchsia, impatiens, single-petal marigolds, nasturtiums, stonecrop sedum and sunflowers. Shrubs and trees include dogwood, fruit trees, june berries, raspberries, red maple, sumac and willows.
More information about encouraging beneficial insects in your garden is available in the OSU Extension publication PNW 550, Encouraging Beneficial Insects in Your Garden.