A partial solar eclipse is about to happen in Vacaville, Calif.
I am watching the insects: the honey bees nectaring on the African blue basil, an orbweaver spider munching on its prey, an assassin bug poised on a tropical milkweed, and a praying mantis lurking beneath a showy milkweed leaf.
Today (Aug. 21) is the long-awaited Great American Eclipse. The totality path will begin at 9 a.m. in Oregon, and stretch across the country to South Carolina.
Hmm, I wonder, how will the bugs in our pollinator garden react to a partial eclipse?
It won't be drastic, I predict. And it wasn't.
The partial eclipse in Vacaville began at 9:02 a.m. and reached its maximum (70 percent coverage of the sun) at 10:16. It ended at 11:38 am., a duration of two hours and 36 minutes.
The bees foraged before, during and after the eclipse, primarily on the African blue basil, which is usually covered with bees. During the height of the eclipse, however, as the skies darkened, a little more than half remained. After the eclipse, when the temperature increased and the wind ceased, the number of bees returned to normal.
"Honey bees tend to act like night is falling if the eclipse takes out quite a bit of the sunlight," says honey bee guru Eric Mussen, Extension apiculturist emeritus and president of the Western Apicultural Society. "Then they 'wake back up' afterwards."
Despite the eclipse, the spider kept eating its prey. (Sure hope it wasn't that blue dragonfly, Libellula luctuosa, "the widow skimmer" I saw yesterday.) The praying mantis kept lurking. The assassin bug raised its antennae. And the bees--although fewer of them--just kept foraging.
Two stink bugs opted to procreate on the bluebeard, Caryopteris x clandonensis. A Gulf Fritillary fluttered by and stopped to sip nectar from the Mexican sunflower (Tithonia). The assassin bug crawled higher on the milkweed, poised for an ambush.
The spider tugged its prey beneath a leaf, abandoning its web. Well, that's that, I thought.
Not so. The sticky web snagged a honey bee while the spider was polishing off its first prey. Okay, spider, you've already had your breakfast. You don't need a second helping. Not today."
I freed the struggling bee and off it buzzed to forage another day.
A partial eclipse, but a full escape...
A fly, oh, my!
On the approval scale, they don't rank nearly as high as honey bees, but some are often mistaken for them.
Take the Eristalis stipator, which belongs to the family Syrphidae, the hover flies.
It's about the same size as a honey bee and it's a pollinator.
We recently spotted this one--a female Eristalis stipator, as identified by senior insect biosystematist Martin Hauser of the California Department of Food and Agriculture--nectaring on tropical milkweed, Asclepias curassavica. The colors are striking--both the colors of the fly and the flowers. It's a striped fly, with black and white bands, one superimposed gold band, and buff-colored hairs piled on the thorax. And the showy flower, aka "blood flower," is red-orange with a yellow hood.
Eristalis is a large genus of approximately 99 species. The Eristalis stipator has no common name, so we just call it Eristalis stipator.
Or a fly.
In real life, insects "get" milkweed.
We all know it's the only host plant of the monarch butterfly--where monarchs lay their eggs--but it's also a a great source of nectar for butterflies and other insects.
Take the showy milkweed, Asclepias speciosa. Native to California, it is found throughout North America, including in our little pollinator garden!
Speciosa nectar is sweet, tantalizing and irresistible.
Recently we've been watching the diversity of insects gathering on our milkweed. Sometimes it's a pushing/shoving match or I'll-fly-away-but-I'll-be-back-as-soon-as-you-leave vow.
Have you ever seen a male Valley carpenter bee, Xylocopa varipuncta, nectaring on milkweed? The male, a green-eyed blond about the size of a queen bumble bee, can't sting. Or as native pollinator specialist Robbin Thorp, distinguished emeritus professor of entomology at UC Davis says--"Boy bees can't sting." He calls it "the teddy bear bee." What could be more cuddly than this little fellow?
So here's this teddy bear bee trying to grab some nectar while honey bees are buzzing around him trying to get their share. He's bigger; they're louder.
And then, the female of this Valley carpenter bee species (she's solid black--the two represent a clear case of sexual dimorphism) comes along and the bees scatter. Our boy bee does, too.
The bees will be back. The nectar is sweet, tantalizing and irresistible.
What a delight to see.
We strolled through milkweed patches in the UC Davis Arboretum Thursday noon and saw them.
The monarch butterflies (Danaus plexippus) are returning from their coastal California overwintering sites. And we're getting new generations.
The UC Davis campus, including the 100-acre UC Davis Arboretum is home to much celebrated flora and fauna, including milkweed and monarchs.
After overwintering along the California coast and in central Mexico, the butterflies flutter north into the United States and Canada in the spring and summer.
However, scientists report that the monarch population in central Mexico declined from 100 million last year to 78 million this year, due to late winter storms, coupled with cold and wet weather, and deforestration.
It's a sure sign of spring, through, when the monarchs return. It's a cause for celebration. Welcome back!
Meanwhile, we're anticipating the arrival of Christine Merlin, assistant professor in Texas A&M's Department of Biology, who will discuss her research on "The Monarch Butterfly Circadian Clock: from Clockwork Mechanisms to Control of Seasonal Migration" when she presents a seminar on Wednesday afternoon, May 31 at the University of California, Davis. The seminar is set from 4:10 p.m. to 5 p.m. in Room 122 of Briggs Hall. Host is molecular geneticist Joanna Chiu, associate professor and vice chair of the UC Davis Department of Entomology and Nematology.
All summer and into fall, we spotted the familiar reddish, black and white bugs scurrying around on our showy milkweed, Asclepias speciosa, and tropical milkweed, Asclepias curassavica.
Showy bugs on showy milkweed.
The ones we saw: the Small Milkweed Bug, Lygaeus kalmii. Like its name implies, it's small, about half an inch long.
They're primarily seed eaters, but they're opportunistic and generalists, says insect migration biologist Hugh Dingle, emeritus professor of the UC Davis Department of Entomology and Nematology, author of the popular textbook, Animal Migration: the Biology of Life on the Move. "They'll get protein from wherever they can find it," he said. Dingle, whose research includes migratory monarchs, said the milkweed bugs not only eat seeds, but they also eat monarch eggs and larvae and the immature stages of other butterflies. Forever the opportunists, they eat other small bugs as well--if the opportunity arises. And they feed on nectar, too.
Some scientists have seen them feeding on insects trapped in the sticky pollen of the showy milkweed.
The bugs, it seem, have few predators. They feed on the toxic milkweed, which makes them distasteful to predators, prey to avoid. Their warning colors (red and black) strike home that fact.
In the fall, as the seed pods burst open, it's a horticulture/culinary war between the milkweed growers and the milkweed bugs. Both want the seeds: the humans to plant them and the bugs to eat them.
(Note: Research shows that the milkweed bug also feeds on other plants. Read about the opportunist Small Milkweed Bug in the Journal of the New York Entomological Society.)