It won't bloom until summer, but already many eyes are on the California buckeye.
The tree's blossoms are poisonous to honey bees. Bees are attracted to them and forage on them, but the end result of the food provisions to the colony can be deformed larval development.
We've seen bee hives within a quarter of a mile of California buckeyes (Aesculus californica). And we've seen honey bees, native bees and other pollinators foraging on the blossoms.
At the recent UC Davis Pollinator Gardening Workshop hosted by the California Center for Urban Horticulture, Extension apiculturist Eric Mussen talked about the poisonous plants. (See PowerPoint presentations.) That led to one workshop participant wondering if the flowers of the California buckeye are poisonous to native bees. (Honey bees are not native; the European colonists brought them to the Jamestown colony, Virginia, in 1622).
Responded Mussen: "My guess: either the native bees that have been in the areas around California buckeye for a long, long time are not poisoned by the pollen or they have been selected (by death of the other genetic types) to avoid the pollen, that eons of natural selection have adapted them to coexist with California buckeye while using their resources."
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, shared: "We know California buckeye nectar and/or pollen is toxic to honey bees from years of experience with managed hives. Toxicity to native bees and other flower visitors is not so easily determined and to my knowledge has not been investigated. The fact that populations of native bees and butterflies visit California buckeye flowers and continue to persist in areas where the tree is a dominant part of the plant community tends to confirm what Extension apiculturist Eric Mussen says about them. Some good research projects here. So we still do not know if it is the nectar, pollen, or both that may be toxic to honey bees, much less to native flower visitors."
According to gardeningguides.com, the seeds in their raw state are poisonous to humans, but native Americans learned to get around that and use them for food. They pounded the seeds into flour and then cooked the mixture. "This tree had multiple cultural uses among California Indian tribes," the website says. "Many indigenous groups utilized buckeye seeds for food, often when other plant food sources were scarce. These tribes included the Costanoan, Salinan, Kitanemuk, Serrano, Wappo, Sierra Miwok, Coast Miwok, Chumash, Kawaiisu, Northern Maidu among others. The Pomo ate the seeds even when other important food plants were plentiful. The seeds are poisonous to humans in the raw state. Thus, the nuts were cracked open with a rock, the shells removed, the seeds pounded into flour, and their toxic saponins removed in a lengthy leaching process. The meal was subsequently cooked and eaten. There are many different methods for processing and cooking buckeye seeds for food, depending upon the tribe. The seeds have medicinal properties and were cut into pieces, mixed with water, and made into suppositories for hemorrhoids by the Costanoan and Kawaiisu. The Pomo cut bark from the base of the tree and made a poultice, which was laid on a snakebite. Young buckeye shoots were sometimes used as spindles or twirling sticks in fire-making kits of the Sierra Miwok, Northern Maidu, Wappo, Yahi and other tribes. Many tribes mashed buckeye nuts and poured the contents into quiet pools to stupefy or kill fish."
And, no wildlife will eat buckeye seeds except squirrels, such as the California ground squirrel (Citellus beecheyi).
Meanwhile, the poisonous blossoms continue to beckon the honey bees--and their colonies keep producing deformed bees.
Indeed, to the untrained eye, the drone fly (Eristalis tenax) appears to be a bee. It's not; it's a fly.
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, calls the drone fly "The H Bee." That's because there's an "H" on its abdomen (see photo). Like all flies, however, it can be distinguished by one pair of wings and stubby antennae. The larva of the fly is a rat-tailed maggot that lives in drainage ditches, pooled manure piles and other polluted water. The adults are floral visitors. Pollinators.
The "H Bee" was among the pollinators that Thorp discussed at the UC Davis Pollinator Gardening Workshop, hosted March 6 by the California Center for Urban Horticulture.
Extension apiculturist Eric Mussen of the UC Davis Department of Entomology and Nematology, switched from bee mimics (drone flies, syrphid flies and other insects) to talk about the "real" honey bees, Apis mellifera, which European colonists introduced to what is now the United States in 1622. "The honey bees' biggest problem today is malnourishment," he said. "A single honey bee colony requires an acre of bloom to meet its nutritional needs each day," he said.
The queen can lay 2000 eggs a day in peak season. "One cell of honey and one cell of pollen make one bee."
He urged the participants to "try to plant for late summer and fall bloom, when honey bees in California are having a hard time finding nectar and pollen resources."
Mussen cautioned that bees are subjected to toxic pollens and unnatural toxins (pesticides). Plants poisonous to bees include the California buckeye (Aesculus californica) death camas (Toxicoscordion venenosum), corn lily (Veratrum californicum) and some locoweeeds (Astragalus spp.)
Pesticides inside the hive (used to control varroa mites) and outside the hives can be fatal. However, he said, "any kind of pesticide a bee encounters--there's always a physiological change."
Following the morning-long speaker presentations, the participants visited the UC Davis Arboretum Teaching Nursery on Garrod Drive to check out and/or purchase Arboretum All-Stars and other plants, and they toured the Häagen-Dazs Honey Bee Haven, a half-acre bee friendly garden on Bee Biology Road that is under the wing of the UC Davis Department of Entomology and Nematology. The garden is located next to the Harry H. Laidlaw Jr. Honey Bee Research Facility.
Among those traveling the longest distance were Lake Tahoe UC Master Gardeners Lynne Broche and Bonnie Turnbull and Turnbull's 14-year-old daughter, Jessie Brown, a junior Master Gardener and an avid insect photographer.
The ceanothus blooming in the haven especially drew the attention of the workshop participants. Insects foraging in the ceanothus included two so-called "H bees"--the honey bee and its impostor, the H-marked drone fly.
They're there for the pollen.
"California poppies provide only pollen--no nectar," native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, told the Pollinator Gardening Workshop last Saturday on the UC Davis campus. Thorp was one of the featured speakers at the event, sponsored by the California Center for Urban Horticulture.
Thorp, who identifies thousands of bees a year for researchers, enthralled the audience with facts about bees. Although he retired in 1994, he maintains an office at the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis, and is one of the instructors of The Bee Course.
Some of the information he presented:
- Unlike wasps, which are carnivorous, "bees are vegans." They gather pollen and nectar from plants. (They also collect water and propolis, or plant resin, for their colonies.)
- "Flowers don't have wings; so we need the pollinators to come to them."
- The global population of bees includes some 19,500 named species. Of that number, about 4000 different species of bees occur in North America; 1600 in California, and more than 300 species of bees in Yolo County. (Over the last four years, Thorp has found more than 80 species of bees in the Häagen-Dazs Honey Bee Haven a half-acre bee friendly garden on Bee Biology Road maintained by the UC Davis Department of Entomology and Nematology.)
- Seventy percent of bees are solitary, and most nest in the soil.
- Fifteen percent of bees are cuckoo bees; the females lay their eggs in other bees' nest and their offspring eat the provisions
- Only 10 percent of bees are social (honey bees are among them)
Thorp recommends that if you want to attract native bees, provide food (bee plants), water and shelter. "Leave some bare soil, avoid mulch madness, and provide bee condos (drilled blocks of wood that blue orchard bees and leafcutting bees use for their nesting sites.)
"Plant it and they will come," Thorp said. "Provide habitat and they will stay and reproduce."
Thorp is the co-author of a newly published book, "Bumble Bees of North America" (Princeton University Press) and a co-author (with Gordon Frankie of UC Berkeley and colleagues) of a pending book with the working title, "California Bees and Blooms."
One of the websites Thorp recommends is the UC Berkeley Urban Bee Lab website, http://www.helpabee.org/, which provides information on native bees, gardening for bees, and current projects and partnerships.
- "I just saw a golden bumble bee. I think it's a new species! Can I name it?"
- "I just saw a huge bee and it's gold in color and all fluffy with green eyes!"
- "I just saw a huge bumble bee flying around in our backyard. It's yellow and I think it's a pest."
It's the male Valley carpenter bee, Xylocopa varipuncta, which native pollinator specialist Robbin Thorp, emeritus professor of entomology at the Department of Entomology and Nematology at the University of California, Davis, calls "the teddy bear" bee.
Like all male bees, it doesn't sting.
But what's unusual about this bee is its color, golden with green eyes. It's sexual dimorphism at its best, because the female Valley carpenter bees are solid black.
The Valley carpenter bee is the biggest carpenter bee in California. And it scares the living beejeez (dead beejeez, too) out of young children, teenagers, and adults. Just about everybody and everything, including the family dog and cat.
As Thorp told us several years ago for a news story:
"Xylocopa varipuncta occurs in the Central Valley and southern California, Arizona, New Mexico and southward through Mexico. It is large (about the size of a queen bumble bee), with all black females and golden/buff-colored males with green eyes. Females have dark wings with violet reflections."
Some folks think it's a pest. It's not. It's a pollinator. Let it "bee."
Monarchs and milkweed are in the news again.
As well they should be.
The declining monarch population, coupled with the decreasing scarcity of their host plant, the milkweed, is disturbing. The larvae of the monarch butterfly (Danaus plexippus) feed exclusively on milkweeds. No milkweed, no monarchs.
Butterfly expert Art Shapiro, distinguished professor of evolution and ecology at UC Davis, says the problem hasn't totally reached California yet. "The 'dearth of milkweed' problem is primarily an East/Midwest problem, due to increased use of Roundup since the introduction of 'Roundup-ready' GM crops. It's quite real. There is no such problem out here--at least yet--but there is a new milkweed pathogen that may cause one! Dave Rizzo (UC Davis Department of Plant Pathology) and I hope to publish on it shortly. No harm in planting milkweeds, but the problem isn't a California one, at least not yet."
Journalist-photographer Alessandra Bergamin, writing in the Feb. 18 edition of Bay Nature: Exploring Nature in the San Francisco Bay Area, says that "the number of monarchs overwintering in Mexico's Oyamel fir forest has reached an all-time low," quoting the World Wildlife Fund in Mexico. "The reports suggest that factors such as loss of habitat, climate change and use of insecticides have contributed to the decline."
The situation in California, however, looked better than bleak last year. A little better. "Monarch butterfly populations in California's coastal overwintering sites showed a slight — and surprising — rebound in 2013 after more than a decade of dwindling numbers," Bergamin wrote. "The 2013 Western Monarch Thanksgiving Count tallied 211,275 monarchs at 162 sites from Sonoma County to San Diego County, up from 144,812 the year before."
Over the past two decades, however, the Western monarch population has dramatically declined in California, she pointed out in her article, "Western Monarch Population Hanging On." The downward trend is expected to continue.
Meanwhile, the Xerces Society for Invertebrate Conservation, headquartered in Portland, Ore., has posted a seed finder resource so folks can find milkweed seed in their state and plant the seeds in their gardens, parks, landscapes, restoration areas and on farms.
Oakland parks supervisor Tora Rocha is taking it one step further. She is collecting the monarch caterpillars, rearing them, and releasing the adults in the Lakeside Gardens at Lake Merritt. Her newly formed Pollinator Posse has sparked the interest of volunteers, who range from school children to city council members. They all want to save the monarchs.
Rocha bans pesticides and herbicides from her pollinator gardens. “For the past fifteen years the gardens have had a pesticide-and herbicide-free policy,” Rocha told writer Constance Taylor of Wild Oakland, which offers free, Oakland-centered environmental education. “We also rely on volunteers contributing thousands of hours to keep our parks maintained--about 75% of the work is done by volunteers.”
Rocha says it's not enough to be a custodian of the land: it's important to be a steward of the land and protect the pollinators. She's created a video, posted on YouTube, that explains what she and the other Pollinator Posse members do.
Rocha and colleague Eddie Dunbar of the Insect Sciences Museum of California and a fellow Pollinator Posse member, recently visited UC Davis to share information with Shapiro and native pollinator specialist Robbin Thorp, emeritus professor of entomology.
Another person keen on butterflies is Sally Levinson of Berkeley, who writes a blog on butterflies and is publishing educational videos, including "Secret Lives of Monarchs" and "In the Company of Wild Butterflies." As a graduate student at UC Riverside, Levinson studied with major professor Bruce Hammock, now a distinguished professor of entomology at UC Davis. (He maintains a joint appointment with the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center.)
As an aside, the Bohart Museum of Entomology at UC Davis offers a "Got Milkweed?" t-shirt spotlighting the monarch and its host plant. The work of doctoral candidate Fran Keller and Bohart volunteer/naturalist Greg Kareofelas, the t-shirt is available online or at the museum, located in Room 1122 of the Academic Surge building on Crocker Lane.
Want monarchs? Plant milkweed.