- Author: Kathy Keatley Garvey
It was a good day for a crab spider.
It was NOT a good day for a honey bee.
It's early evening and here's this bee foraging on a bluebeard plant, Caryopteris x clandonensis, totally unaware of the ambush predator lying in wait.
The predator and the prey: Misumena vatia and Apis mellifera.
The hunter and the hunted.
A venomous bite and it's all over.
These spiders, often called the "white death spider," are camouflage artists. They can turn colors, from yellow to white, or white to yellow. You'll often see yellow crab spiders on golden rod Solidago or a predominantly yellow plant, like blanketflower, Gallardia.
"These spiders change color by secreting a liquid yellow pigment into the outer cell layer of the body," according to Wikipedia. "On a white base, this pigment is transported into lower layers, so that inner glands, filled with white guanine, become visible. The color similarity between the spider and the flower is well matched with a white flower, in particular the Chaerophyllum temulum, compared to a yellow flower based on the spectral reflectance functions."
"If the spider dwells longer on a white plant, the yellow pigment is often excreted," Wikipedia says. "It will then take the spider much longer to change to yellow, because it will have to produce the yellow pigment first. The color change is induced by visual feedback; spiders with painted eyes were found to have lost this ability. The color change from white to yellow takes between 10 and 25 days, the reverse about six days. The yellow pigments have been identified as kynurenine and 3-hydroxykynurenine."
Who knew?
One thing's for sure: everybody eats in the pollinator garden.
- Author: Kathy Keatley Garvey
What's for dinner?
A crab spider, camouflaged in our lavender patch, didn't catch a honey bee, a butterfly, an ant or a syrphid fly.
No, it nailed a green bottle fly.
We couldn't help but notice. The fly's metallic blue-green coloring stood in sharp contrast to the white spider.
One venomous bite to kill it. And soon the fly, Lucilia sericata, was toast. Milk toast.
Crab spiders don't build webs to trap their prey. They're cunning and agile hunters that spring into action when an unsuspecting prey appears on the scene. They belong to the family Thomisidae, which includes some 175 genera and more than 2100 species. And they're ancient: spiders date back 400 million years ago.
Do you like spiders? You should.
“Spiders are an incredibly diverse group with more than 50,000 species described with probably another 200,000 remaining to yet be discovered,” says spider expert Jason Bond, the Evert and Marion Schlinger Endowed Chair in Insect Systematics in the UC Davis Department of Entomology and Nematology.
It's worth repeating what Professor Bond said about spiders at the Bohart Museum of Entomology open house, “Eight-Legged Wonders,” on Saturday, March 9.
The five good reasons to like spiders:
- Spiders consume 400-800 million tons of prey, mostly insects, each year. Humans consume somewhere around 400 million tons of meat and fish each year.
- Spider silk is one of the strongest naturally occurring materials. Spider silk is stronger than steel, stronger and more stretchy than Kevlar; a pencil thick strand of spider silk could be used to stop a Boeing 747 in flight.
- Some spiders are incredibly fast – able to run up to 70 body lengths per second (10X faster than Usain Bolt).
- Athough nearly all 47,000-plus spider species have venom used to kill their insect prey, very few actually have venom that is harmful to humans.
- Some spiders are really good parents –wolf spider moms carry their young on their backs until they are ready to strike out on their own; female trapdoor spiders keep their broods safe inside their burrows often longer than one year, and some female jumping spiders even nurse their spiderlings with a protein rich substance comparable to milk.
- Author: Kathy Keatley Garvey
Henrietta, our Stagmomantis limbata praying mantis, perches on a Mexican sunflower (Tithonia).
She is as patient as she is persistent.
The drone fly, aka syrphid and also known as a hover fly or flower fly, makes the fatal mistake of touching down on the same blossom.
Henrietta eyes it hungrily. Faster than a blink of the eye, she snares it, clutching it between her spiked forelegs.
"Well, of course, I like drone flies," she appears to be saying, between mouthfuls. "Thank you for asking."
Praying mantids are not known for their table manners. It's grab, hold and eat.
The cycle of life in the garden.
- Author: Kathy Keatley Garvey
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...
- Author: Kathy Keatley Garvey
Ever seen assassination attempts in your garden?
They are not pretty if you're the prey. Neither are the successful attempts.
Take the Zelus renardii, aka the leafhopper assassin bug.
They've been hanging out in our nectarine tree, cosmos, passionflower vine and Cleveland sage. They stalk or lie in wait and then jab their prey with their long rostrum, injecting a lethal saliva. Next: they suck out the contents. They "assassinate" such pests as aphids, leafhoppers, and caterpillars of the cabbage white butterfly.
Assassin bugs also feed on beneficial insects, too, such as bees, lacewings and lady beetles, aka ladybugs.
They're often confused with kissing bugs. Can "assassin bugs can carry Chagas disease, which can transmit to humans?" a reader asked.
We asked noted entomologist Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis, for comment and clarification.
"Assassin bugs and kissing bugs belong to the same family of insects, the Reduviidae," Kimsey said. "However, biologically they are very different. Kissing bugs belong to 20 or more species in the subfamily Triatominae. They are nocturnal blood feeders, and you almost never see them during the day. Most of these species in California are infected with the protozoan that causes Chagas disease, but because of differences in how they feed, few if any can actually transmit it to humans."
"The pathogen is transmitted in their droppings and have to be inhaled or scratched into the skin," Kimsey pointed out. "This only happens if the kissing bug defecates during feeding. The California species do not defecate until they leave the host and go back to a resting site, so the chances of getting Chagas disease from a bug in California are cosmically small. The assassin bugs you see during the day belong to an entirely different group of reduviids. They are all predators on other insects. Some of them, like the common garden assassin bug Zelus, are irritable biters but they do not transmit any kind of pathogen to anything."