- Author: Kathy Keatley Garvey
You can't always choose your tenants.
Sometimes they choose you.
Take the case of our two bee condos, which are blocks of wood drilled with holes for native bee occupancy. One, with the smaller holes, is for leafcutter bees (Megachile spp.) The other, with the larger holes, is for blue orchard bees (Osmia lignaria), fondly known as BOBs.
The leafcutter bees were the first to occupy the bee housing. At one time we had 16 leafcutter bees and one earwig.
The blue orchard bee condo now has three tenants: two BOBs and one spider.
The webweaving spider spun its web and then crawled into the hole for the night to wait for morning.
And to wait for unsuspecting prey.
(Like to learn more about bee condos? See the Harry H. Laidlaw Jr. Honey Bee Research Facility website, UC Davis. Native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, compiled the list of resources.)
- Author: Kathy Keatley Garvey
If you've ever watched spiders trap their prey in their sticky webs, you've probably wondered: "Why don't spiders stick to their own webs?"
We've watched countless spiders trap honey bees, syrphid flies and other hapless critters in their webs. The spiders scamper up and down the webs as their victims furiously try to escape.
Now researchers at the Smithsonian Tropical Research Institute, headquartered in Panama City, and the University of Costa Rica have discovered why spiders don't stick to their webs.
The spiders' legs are "protected by a covering of branching hairs and by a non-stick chemical coating," the scientists announced in the journal Naturwissenschaften (The Science of Nature) and on EurekAlert.
Wrote Beth King of the Smithsonian Tropical Research Institute: "They also observed that spiders carefully move their legs in ways that minimize adhesive forces as they push against their sticky silk lines hundreds to thousands of times during the construction of each orb."
Furthermore, the scientists recorded the webweaving behavior on video. The camera showed that "Individual droplets of sticky glue slide along the leg's bristly hair."
So now one of the most common questions (next to "Why is the sky blue?" and "Why is the grass green") has been answered.
Check out the videos on the EurekAlert website.
- Author: Kathy Keatley Garvey
Mama said there'd be days like this,
There'd be days like this, Mama said...
When Van Morrison wrote the lyrics to "Days Like This," a song popularized by The Shirelles, he probably wasn't thinking of a mama garden spider or her prey.
Still, when Mama Spider weaves her web and snares three pollinators in two days, that's a "Wow." A double, triple "Wow!"
Garden spiders are good to have in the garden when they're capturing and eating pests, like flies, knats, mites, lygus bugs, katydids and the like. Just wish they'd quit picking on the pollinators.
Still, Mama has to eat.
- Author: Kathy Keatley Garvey
It was not a good day to be a honey bee.
But it was a good day to be a spider.
For days we watched honey bees, sweat bees and syrphid flies visit a patch of alyssum and African daisies in our yard. Their floral visits did not go unnoticed. A crafty spider stretched a web between two citrus trees just above the flowers.
The spider waited patiently, sometimes dangling in the middle of the web, sometimes tucked beneath the citrus leaves. The web seemed more like a fishing net than a trap because, under our watch, she caught nothing.
Her prey easily slipped through the net and bounced out of harm's way.
Not so on Saturday. A honey bee encountered the sticky web and could not escape--neither the sticky web nor the spider's bite. By the time we saw the bee, she was already toast...well...spider dinner.
It was not a good day to be a honey bee.
But it was a good day to be a spider.
- Author: Kathy Keatley Garvey
The very presence of a black widow spider, shiny black with a globe-shaped abdomen, strikes fear in most people.
And not just on Halloween.
"Many spiders will bite when trapped but black widow spiders (Theridiidae: Latrodectus) are the most dangerous North American species," write Charley Eiseman and Noah Charney in their newly published book, Tracks and Sign of Insects and Other Invertebrates: A Guide to North American Species.
"Their strong venom can kill," agrees George C. McGavin in the Smithsonian Handbooks' Insects, Spiders and Other Terrestrial Arthropods, "but a fast-acting antivenom can be given by injection."
The black widow is a cobweb spider and "the females produce about 200 to 250 eggs, attached to the web in a sac," McGavin says.
So, where can you find black widow spiders? They're usually in more concealed places than the common house spider, which is "found in any dry structure, including houses, basements an barns, as well as under natural 'roofs' such as overhanging ledges," according to Eiseman and Charney.
And, Eiseman and Charney point out, the black widow spider webs are "composed of extremely strong, coarse threads"--unlike those of common house spiders.
McGavin says black widow spiders are commonly found in leaf litter, under stones and in and around buildings.
We sighted one under leaf litter recently at the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis. Its distinguishing mark: the reddish-orange hourglass on its stomach.
Then last week we spotted a black widow spider guarding her gumdrop-sized sac in a secluded area of a UC Davis parking garage.
She didn't pay attention to the "permit parking only" signs.