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Meet the New Tenant
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.)
Webweaver spun a web and then crawled into the mason bee condo to occupy a hole. (Photo by Kathy Keatley Garvey)
Close-up of webweaving spider occupying space in the bee condo. (Photo by Kathy Keatley Garvey)
Sticky Business
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.
A garden spider spinning a web. (Photo by Kathy Keatley Garvey)
Garden spider wrapping its prey. (Photo by Kathy Keatley Garvey)
Two for One
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.
Mama spider snares two in one web. (Photo by Kathy Keatley Garvey)
Not a Good Day to Be a Bee
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.
Spider crawls toward its prey, a honey bee. (Photo by Kathy Keatley Garvey)
Spider dining on a honey bee. (Photo by Kathy Keatley Garvey)
Brown widow spider could be a concern for farmers
“The brown widow is spreading like wildfire,” said UC Riverside urban entomologist Rick Vetter. "It’s a very prolific pest. People find them by the hundreds in places where they haven’t seen spiders before.”'
The brown widow poses less of a health threat than black widows, but Vetter said there are several reasons why the agricultural community should be concerned about their potential northward migration. Currently little is known about brown widow spider biological control. While black widows prefer low hangouts, it is not yet known whether brown widows will adjust to higher posts in California. If the spiders take up residence in fruit orchards, for example, they could pose a problem for farmworkers.
“Pickers and harvesters won’t want to have these spiders falling down on them,” Vetter said.
Brown widows could also potentially congregate in agricultural shipping containers or packaging.
Brown widow spiders are native to Africa and are established in tropical environments throughout the world. They have been found in Florida for many decades, but only recently expanded their range from Texas through South Carolina, and into Southern California. As of 2009, the spider was established in Los Angeles, Orange and San Diego counties, and in 2010 it made its way to Riverside, San Bernardino, Ventura and Santa Barbara counties. There have been a few finds in areas further north.
“I’ve gotten three females from Sacramento and three females from Washington (state),” Vetter said. “I’ve gotten no other spiders from those areas, so I don’t know if they will be another infestation area or not.”
Vetter is asking the public to assist in his brown widow spider research by carefully following instructions for collecting and sending brown widow spider specimens to the university. Potential spider collectors should study the photos on his website to learn the characteristics of brown widows. Because the spider is already established in Southern California, Vetter does not need specimens from San Diego, Orange, Los Angeles and the Riverside and San Bernardino-Redlands area. More specimens are welcome from Ventura, Santa Barbara, from Riverside and San Bernardino counties outside of the urban cities in the western part of the counties and from all the rest of California.
For spider shipping instructions, see Vetter’s brown widow spider research page.
Watch an 80-second video for tips on identifying brown widow spiders:
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