Habitat loss has contributed to a dramatic decline in the population of Crotch’s bumblebee (Bombus crotchii). This individual was documented foraging on Bog Sage (Salvia uliginosa) near the Children’s Garden. Photo by Sandy Masuo. | The Huntington Library, Art Museum, and Botanical Gardens.
The robust array of plants at The Huntington is much more than a feast for our senses; the gardens feature many flowering plants that attract an amazing variety of pollinators. Although many animals perform this role, nature’s preeminent pollinators are insects. As temperatures increase and peak bloom season unfolds, the gardens draw pollinators as diverse and delightful as the plants they visit. Some are familiar, while others may surprise you. And since National Pollinator Week (June 17–23) is right around the corner, now is the time to take a close look in the gardens for pollinators at work.
Humans began keeping honeybees more than 7,000 years ago, around the same time that horses were domesticated. In Southern California, honeybees forage year-round on a range of plants. Photo by Sandy Masuo. | The Huntington Library, Art Museum, and Botanical Gardens.
Bees are the best-known group of pollinators, and the most recognizable of these is the European honeybee (Apis mellifera). Native to Europe, Asia, and Africa, honeybees were introduced to North America in the 17th century by European colonists. Because they produce large stores of honey and live in enormous colonies comprising tens of thousands of individuals, honeybees can maintain their body temperatures in cold winter climates and forage year-round in Southern California. Quite distinct from honeybees, the native bees found at The Huntington are generally solitary and active only during spring and summer. Since they do not live in hives, male solitary bees often sleep in flowers at night, while females settle into the nests they construct for their eggs—nests located underground, in hollow plant stems, or in fallen logs and branches.
Left: In solitary bee species, females sleep in the nests they create for depositing their eggs, while males, like this long-horned bee (Melissodes sp.), often spend the night on flowers. Right: California Buckwheat (Eriogonum fasciculatum) attracts many pollinators, including honey-tailed striped sweat bees (Agapostemon melliventris). Photos by Sandy Masuo. | The Huntington Library, Art Museum, and Botanical Gardens.
Some bees (including honeybees) are generalists and pollinate a range of plants; others specialize in particular plant families. For example, bees in the genera Peponapis and Xenoglossa forage exclusively on plants in the squash family. They pollinate such California natives as coyote melon (Cucurbita palmata) and wild gourd (Cucurbita foetidissima). They are commonly seen in The Huntington’s Kitchen Garden when the domestic squashes are in bloom. Fortunately, the gardens at The Huntington have a range of plants that appeal to both specialist and generalist pollinators.
Bumblebees, like this black-tailed bumblebee (Bombus melanopygus), pollinate many plants that honeybees are unable to pollinate, including important crop plants and endangered wildflowers. Photo by Sandy Masuo. | The Huntington Library, Art Museum, and Botanical Gardens.
Bumblebees are significant because they can pollinate some plants that most bees cannot, including such important crops as blueberries, cranberries, and tomatoes. These plants have closed tubes that conceal pollen, which is only released for bees that can vibrate their flight muscles at a certain frequency—a process called sonication or buzz pollination.
Because bumblebee populations are small to begin with and their annual life cycle is unusual, they are hard hit by the threats that affect all pollinators, particularly habitat loss. These semi-social bees live in colonies of 50 to 500 individuals. In spring, the foundress queen builds a nest (usually underground) comprising little wax pods that she provisions with nectar and pollen before she lays her eggs. The first larvae to hatch are female workers. Once the workers emerge, the queen can stop foraging and remain in the nest because the workers will tend to her and the colony. As summer wanes, the queen lays eggs that will produce potential queens (gynes) and males. These emerge and disperse to mate. By fall, the foundress queen, the workers, and the males all die, leaving the newly mated queens to overwinter and start the cycle all over again.
Unlike solitary bees, which nest in small nooks and survive by overwintering as larvae, a colony of bumblebees depends for survival on its lone foundress, which must overwinter and then establish a nest in spring. In addition to the myriad flowering plants that gardens offer, perimeter areas and buffer zones provide important nesting sites for bumblebees. In 2022, four bumblebee species were selected to be considered for protection under the California Endangered Species Act. One of these, Crotch’s bumblebee (Bombus crotchii), was documented at The Huntington last year.
Left: At first glance, a Mexican cactus fly (Copestylum mexicanum) can pass for a carpenter bee. Right: However, when compared with a female Valley carpenter bee (Xylocopa sonorina), differences in antennae length, eye shape, and wings become clear. Photos by Sandy Masuo. | The Huntington Library, Art Museum, and Botanical Gardens.
Some “bees” are actually imposters, like flower flies, of which about 300 species exist in California. Like the bees they often resemble, they feed on nectar and pollen. Their misleading appearances are adaptations that help them avoid being eaten; potential predators might steer clear of a striped flying insect for fear of being stung. But flower flies can be distinguished from bees by three main features: short, stubby antennae (bees have long antennae, often with a distinct bend in the middle); one set of wings (bees have two sets); and large, goggle-like eyes that often meet on their foreheads (bees have two oval primary eyes plus three tiny “ocelli,” or simple eyes, on their foreheads).
Left: Adult mason wasps (Euodynerus hidalgo viereckii) consume nectar, but they feed their larvae caterpillars. Photo by Sandy Masuo. Right: Some wasps, such as the tarantula hawk (Pepsis thisbe), capture spiders for their young. Photo by John Trager. | The Huntington Library, Art Museum, and Botanical Gardens.
Wasps not only resemble bees but are close relatives: Bees branched off from the wasp lineage roughly 120 million years ago. Adult wasps consume nectar and honeydew (a sugary secretion produced by aphids and other sap-sucking insects), but, unlike bees, they do not feed their offspring nectar and pollen. In almost all species, wasp larvae are carnivorous and feed on insects and spiders provided by the parent. (Worker wasps in social species are also nectar feeders but will scavenge and feed carrion and other protein sources to the larvae.) Because they do not need to stockpile pollen for their future offspring, wasps transfer it only incidentally as they feed on flowers.
Left: The green figeater beetle (Cotinis mutabilis) is known for eating fruit, but it also consumes pollen, transferring some from flower to flower in the process. Photo by Sandy Masuo. Right: This tiny weevil (Parallocorynus inexpectatus) pollinates Dioon cycads. Photo by Sean Lahmeyer. | The Huntington Library, Art Museum, and Botanical Gardens.
Beetles account for roughly 25% of all known animal species and occupy a wide range of ecological niches, including those of pollinators. Many weevils, a family of beetles distinguished by their long snouts, are agricultural pests, but some are beneficial, pollinating such plants as orchids, palms, and cycads. Dioon, a cycad genus native to Mexico, is well represented in The Huntington’s living cycad collection. Botanical staff members were hand pollinating Dioons as part of a research and conservation project when they discovered that a weevil in the genus Parallocorynus, known to pollinate Dioons in the wild, had naturalized in the gardens. How the weevil came to The Huntington is unknown, but it originates in the same habitat as the Dioon cycads.
Left: Most butterflies, like this monarch (Danaus plexippus), are not very effective at moving pollen from flower to flower. Right: The moth-like fiery skipper (Hylephila phyleus) butterfly has a compact, fuzzy body that more easily picks up pollen. Photos by Sandy Masuo. | The Huntington Library, Art Museum, and Botanical Gardens.
As beloved as butterflies are, they are less effective pollinators than other insects. With their long legs and coiled tongues, they can barely contact flowers’ pollen-laden parts. Butterflies’ nocturnal cousins, moths, are more proficient pollinators; their compact, fuzzy bodies more readily pick up pollen as they forage. However, butterflies make up for their lack of pollination prowess with charisma, inspiring people to plant food sources for them. Creating diverse gardens that support butterflies also provides resources for many less glamorous pollinators.
As you enjoy the spring and summer bloom season at The Huntington, be sure to take time to appreciate the profusion of pollinators that help make the floral spectacle possible.
Many native bees are extremely small and move so quickly that they are almost invisible. This fairy bee (Perdita rhois) is foraging on a Toyon (Heteromeles arbutifolia) flower that is only a few millimeters wide. Photo by Sandy Masuo. | The Huntington Library, Art Museum, and Botanical Gardens.
How to help pollinators:
• Provide diverse flowering plants that bloom throughout the year, and be sure to include some native species.
• Avoid pesticides and herbicides, or choose options that are less toxic.
• Allow insects and other wildlife to overwinter under leaf litter in out-of-the-way corners of your garden.
• Leave a few patches of bare earth, some spent annuals, and a branch or two in your garden to provide nest sites for the next generation of pollinators.
Sandy Masuo is the botanical content specialist at The Huntington.