Honey bees are the first thing you notice about the sea squill (Drimiamaritima or Urginea maritima) in the 100-acre UC Davis Arboretum and Public Garden.
The sea squill, thriving in the Carolee Shields White Flower Garden and Gazebo, is a bee magnet, not to mention it's an incredible flowering plant in an incredible place.
As it says on the Arboretum website: "The Carolee Shields White Flower Garden and Gazebo is a theme garden based on medieval moon-viewing gardens of India and Japan. With its curving paths framing a vine-covered gazebo, the garden is a popular site for weddings and other events. Many of the plants here are fragrant, and their pale flowers are particularly luminous by moonlight. The garden is named for Carolee Shields, an avid gardener and the wife of Judge Peter J. Shields, one of the founders of the UC Davis campus."
The plant grows from a large bulb that produces a raceme of flowers. It's native to southern Europe, western Asia, and northern Africa. Since ancient times, it's been used as a medicinal plant. Hippocrates reportedly used it to treat jaundice, convulsions, and asthma. The main active compounds, according to Wikipedia, are cardiac glycosides.
And did you know that the plant has also been used as a poison? "It is very bitter, so most animals avoid it," Wikipedia tells us. "Rats, however, eat it readily, and then succumb to the toxic scilliroside. This has made the plant a popular rodenticide for nearly as long as it has been in use as a medicine. The bulbs are dried and cut into chips, which can then be powdered and mixed with rat bait. The plant was introduced as an experimental agricultural crop in the 20th century primarily to develop high-toxicity varieties for use as rat poison.]nterest continued to develop as rats became resistant to coumarin-based poison."
If you've ever stepped in sticky gum, it's similar to what happens when an insect steps into milkweed pollinia.
Take the wasps visiting the tropical milkweed (Asclepias curassavica) on Thursday morning, July 16 in the UC Davis Arboretum and Public Garden.
They foraged on the colorful red, yellow and orange blossoms, and as nature intended (for reproductive reasons), flew off with that sticky pollinia from the anthers.
Basically, pollinia is a sticky packet of golden pollen grains originating from a single anther. The wishbone-shaped pollinia are in a nectar trough where insects often get trapped. Some insects manage to escape but leave body parts behind. A foot here...a wing there...an antenna over there...
One wasp exited a flower with "the golden glue" on its feet.
“Too funny with all the milkweed pollinia all over its feet,” commented Lynn Kimsey, director of the Bohart Museum of Entomology and Nematology and professor of entomology at UC Davis, who identified the wasp as a species of Podalonia, parasitoidal wasps in the family Sphecidae. "It looks like it's wearing fluffy socks.”
We've seen honey bees on showy milkweed (Asclepias speciosa) struggling to free themselves, only to find the bees dead the next day--and new recruits buzzing in for their share.
These Podalonia wasps, however, managed to navigate the "traps" quite well.
They'll be back for another round.
(Reminder: Folks planting the tropical milkweed in temperate zones (like here in Davis, Calif.) must remove or cut back the tropical milkweed by winter. "A protozoan parasite of monarch butterflies, Ophryocystis elektroscirrha or OE for short, can travel with monarchs visiting the plants and become deposited on leaves," explains the Xerces Society for Invertebrate Conservation.)
She probably eats a lot of mosquitoes.
After all, we just observed National Mosquito Control Awareness Week, June 21-27, didn't we?
We spotted this female widow skimmer dragonfly (Libellula luctuosa) on Friday morning, June 26 in the Ruth Risdon Storer Garden of the UC Davis Arboretum and Public Garden. She flashed her steel-blue coloring and her black basal-banded wings as she zig-zagged from one perch to the other, catching and consuming flying insects.
Naturalist-photographer Greg Kareofelas, an associate of the Bohart Museum of Entomology, UC Davis, identified the gender and confirmed the species. "I think this is a very good year for them," he told us. Last week he and a colleague observed many widow skimmers, both male and female, in West Davis.
"The species name means sorrowful or mournful, perhaps because the wings of both male and female seem to be draped in mourning crepe," according to BugGuide.Net. "Females and immature males have the same brown wing bands as the mature males, but not the whitish areas. Wings usually have a brown tip. A dorsal view of the abdomen shows a brown band at center with a yellow stripe running along each side."
Widow skimmers are found throughout the United States except for the Rocky Mountain region, says BugGuide.Net. Their range also includes southern Ontario and Quebec.
Locally, look for these dragonflies near Putah Creek, which flows through the 100-acre UC Davis Arboretum. These species are most commonly seen in the summer, and what a treat to see.
Mosquitoes might think otherwise, though.
The "Tiger King" has nothing on the Western Tiger Swallowtail.
The colorful yellow and black butterfly, Papilio rutulus, reigns supreme. We saw this one last week at the Ruth Storer Garden in the UC Davis Arboretum and Public Garden.
"The Western Tiger Swallowtail is basically a species of riparian forest, where it glides majestically back and forth along the watercourse," writes butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology, on his website. "It has expanded into older urban neighborhoods where several of its host genera are grown as shade trees, and behaves as if the street were a watercourse. In the high country and on the Sierran east slope its usual host is Aspen."
We've seen it glide majestically and forage on everything from Verbena to lilacs (Syringa) to the butterfly bush (Buddleja). What a treat--especially during the coronavirus pandemic! When you visit the Arboretum, keep your social distance and wear facial masks, per the Yolo County Health Department's current precautions.)
Meet the real Tiger King: the Western Tiger Swallowtail./span>
Macro insect photographer extraordinaire Allan Jones captured an image of a female black-tailed bumble bee, Bombus melanopygus on Monday, Jan. 6 on the UC Davis campus.
- The time: 1:45 p.m.
- The place: On white manzanita, just east of the 0ld Redwood Grove past the Old Davis Road/Arboretum Drive entrance, UC Davis Arboretum and Public Garden
- The temperature: About 56 degrees
"From the looks of her pollen load, she has been out collecting for some time now, so she must have been collecting earlier when it was colder yet," Jones reported. He saw one yesterday (Jan. 5 in Davis) west of El Macero but the bumble bee flew before he could photograph it. "I figured the black-tail ground nests were warmed up enough so they would be out early."
Jones, who worked closely with global bumble bee authority Robbin Thorp (1933-2019), distinguished professor of entomology at UC Davis, explained the warming of the nests:
"One summer while shooting bees soon after dawn at a lavender farm in the foothills, the first flight of bees were the bumble bees. Once it warmed up some, the honey bees showed up. So a few years ago I asked Robbin why on chill winter days I was seeing lots of honey bees, but no bumble bees. (Of course I was eager to win our contest.)
"He explained that bumble bees often nest facing north so that in cold mountainous climates, the warm southern sunshine does not warm their nests and lure them into a sudden drop in temperature or a snow squall that would kill them. Instead they wait for the ground and their nest to warm a bit before they venture out. It was Robbin's reasoning that lead me to believe that yesterday's B. melanopygus sighting in South Davis proved that local nests were warm enough that they would be flying with honey bees in the low '50s. A few years ago, the winner went out and got a shot on a day with very low temperatures as well, but she was on campus where buildings produce some tropical microclimates. This year I decided to get out early."
A little bit about the contest: Thorp launched the contest in 2012 with a small group of bumble bee enthusiasts/photographers: Allan Jones and Gary Zamzow of Yolo County, and yours truly of Solano County. Later UC Davis doctoral student Kim Chacon with the Geography Graduate Group (and on track to receive her doctorate in June 2020), joined the group. Chacon, who studies "habitat connectivity issues for bees at a landscape scale" (see her website on Resilient Bee Landscapes), worked closely with Thorp until his death in June 2019. She is a 2018 alumnus of The Bee Course, co-taught by Thorp.
The rules are simple: the first one who photographs the first bumble bee of the year in Yolo or Solano County wins the title! (No reward, just bragging rights)
The first bumble bee to emerge in this area is the black-tailed bumble bee, Bombus melanopygus. Native to western North America and found from California to British Columbia and as far east as Idaho, it forages on manzanitas, wild lilacs, wild buckwheats, lupines, penstemons, clovers, and sages, among others.
Thorp, a member of the UC Davis entomology faculty for 30 years, from 1964-1994, achieved emeritus status in 1994 but continued to engage in research, teaching and public service until a few weeks before his death. In 2014, during his retirement, he co-authored two books, Bumble Bees of North America: An Identification Guide and California Bees and Blooms: A Guide for Gardeners and Naturalists. He co-taught The Bee Course from 2002 to 2019. This is an intensive nine-day workshop affiliated with the American Museum of Natural History and held annually at the Southwestern Research Station, Portal, Ariz. It's geared for conservation biologists, pollination ecologists, and other biologists who want to gain greater knowledge of the systematics and biology of bees.
The 100-acre UC Davis Arboretum and Public Garden, spanning the 5300-acre campus, is a landmark on the UC Davis campus--and traces its beginnings to more than 80 years ago. As the website says, it includes "demonstration gardens and scientific collections as well as the Putah Creek Riparian Reserve – a rare stream and grassland ecosystem managed for teaching, research, wildlife and habitat protection."
Go visit the Arboretum--and be sure to look for the bumble bees!