Beams from flashlights and smartphones bobbed around the Cable Community Centre, poking into all the nooks and crannies, scanning window frames and exploring under the eaves. Dusk had fallen quickly while we listened to Larry Weber—author of “Spiders of the North Woods,” retired middle school teacher, and ultra-enthusiastic naturalist from northern Minnesota—show slides of local spiders. Now we were looking for the real things – not just photos.
Shouts of “Oh wow!” “What’s this?” “Good find!” and “Everyone should get a good look at this one!” cut through the evening air. Larry spotlighted a particularly messy corner. There, a completely unorganized jumble of threads glistened. “Cobweb spider,” he stated, pointing to the tiny dot of a creature sitting in the mess. “You probably know some humans who keep their homes really tidy,” he explained with a twinkle in his voice, “and some that don’t.” These spiders don’t.
You can often find cobweb weavers in dark corners inside and outside buildings. They have plump, round abdomens, and usually hang upside down in their web--waiting for prey. During the day, they may hide, so the best time to see them is after dusk. Earlier that afternoon we found several empty cobwebs in the bark crevices of a huge white pine, when Larry led us on a spider hunt at the Museum’s Wayside Wandering Natural Play Area.
It was a day just packed full of spiders. The crown jewel of our afternoon spider hunt was a giant yellow crab spider, so named because of the way it holds its large front legs. In early summer, Larry finds crab spiders on daisies, he said, and they are white. By later in the summer, when the coreopsis, goldenrod, and other yellow flowers dominate, he finds mostly yellow crab spiders. They are the same spider, just with the amazing ability to change color slightly to match the flower in which they hide.
Crab spiders can make silk - and Larry demonstrated that by dangling a smaller crab spider by its dragline - but they don’t spin webs. Why bother when you can hide in a flower and just wait for a pollinator to come to you?
However, a beautiful web can endear even the most dedicated arachnophobe to spiders for at least a moment. According to Larry, the perfect web is on a two dimensional plane, with not a single thread broken, and completely covered with dew. Those webs, with the radiating spokes, spiraling threads, and beautiful symmetry, are the creations of orb weaver spiders.
Each evening (or morning, depending on the species) the orb weaver will spin a new web, and a few hours later, it is gone again. What happens to it?
If the spider is successful, insects fly into the sticky, elastic threads of the spiral and get caught while struggling. The spider can rush forward and throw out sheets of swathing silk to subdue the insect. If the catch is large, the spider may wait patiently until the insect has exhausted itself in the struggle. Then the spider injects venom through its fangs to further subdue the insect, follows that with a dose of digestive juices, and finally slurps up an insect smoothie into its sucking stomach.
After all that, the web is usually pretty torn up. Indeed, many spiders will eat their web each day. The silk proteins are then recycled for use in their next web.
Larry’s perfect web--with no threads broken--is an unsuccessful web with a hungry spider.
But we don’t need perfection to enjoy spider webs covered with dew. Mid-summer is when the spiderlings are hatching and growing, and many tiny webs may cover your lawn each morning. The funnel-shaped sheet webs you see in the grass are made by funnel weavers. If you watch closely, you may notice that the webs increase in size each week as the little spiderlings grow up.
Funnel webs aren’t sticky, but they allow the spider, lying in wait at the base of the funnel-shaped retreat, to feel the vibrations of a passing insect, run out, and grab it. Funnel weavers aren’t fans of cold weather, and they scurry indoors on cool nights. You may wake to find one trapped in the smooth porcelain jail of your bathtub or sink. They are harmless, and easily moved back outside with a cup and piece of paper.
If you have bushes in your yard, you probably have “bowl and doily” webs made by the sheet web weavers, too. The web consists of a horizontal platform with many anchoring threads in a delicate maze above. The spider waits below the platform, and may pull its catch right through the bottom of the web.
Late July is the perfect time to spend some time admiring the delicate artistry of our eight-legged, two-body-parted friends. Their wonderful webs catch mosquitoes, moths, and other pesky insects, while adding breathtaking beauty to our early morning walk.
To find out even more amazing facts about spiders and their webs, you can check out Larry Weber’s book, “Spiders of the North Woods,” and visit the Museum’s current exhibit: Nature’s Superheroes—Adventures with Adaptations.
For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! The current exhibit, “Nature’s Superheroes—Adventures with Adaptations,” opens in May 2014 and will remain open until March 2015.
Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com.