Monday, November 5, 2018

Along Came a Spider

Orchard Orbweaver Spider

I love the fall. Cooler and drier temperatures make it a lot more pleasant to walk outside, watching for migratory birds and butterflies. Wildflowers like asters and Wingstem look pretty against the ripening grass and colorful leaves. And insects and spiders that hatched in the spring and matured all summer are feeding to fatten up enough to lay eggs for next spring's brood. When the school nature walks start up again at the nature center each fall, I tell the children that one reason I need to be the leader is so that I can get a face-full of spiderwebs before they do! Starting in about September, any fall morning walk on a trail involves much arm waving and face wiping to remove the spider webs stretched during the night.

Argiope Orbweaver Web is pretty against the brown grass

This time of year I find spiders and their signs all over. Webs stretched from trees, from buildings, covered with dew and full of drifting seeds. I've found funnel webs and chains of mummified remains of insect meals. A jumping spider took up residence in our porch. And an enormous Dark Fishing or Nurseryweb spider appeared at the entryway to the nature center, greeting all visitors for an entire afternoon.

Orbweaver spider in a porch window

Spiny Orbweaver spider web festooned with Burnweed seeds

Funnel Spider web

Past spider meals
Fishing Spider on the wall

Jumping Spider in my porch

Some people are really scared of spiders. I don't blame them. They are strange looking and hairy, and they have an unfair reputation for biting. (Mostly, if you leave them alone, they leave you alone.) I was looking up something about Little Miss Muffet when I chose the title for this post, and found that some people think she was the real daughter of an entomologist, Dr. Muffet, whose spiders scared her. Personally, though, I think spiders are marvelous and beautiful. I don't think I really appreciated them until I moved to Florida and was introduced to the glorious Golden Silk Orbweaver (sometimes called "Banana") Spider that spins her strong golden webs that can stretch a couple of feet in diameter and are strong enough to catch a lizard. They would set up in the treetops, between the utility lines, and often on the side of our house, sometimes just outside a window. All summer I would watch the females as they grew huge, feeding and tending their webs, eventually affixing a big fuzzy egg sac nearby. I watched the strangely small male spiders stay out of the way, and the shiny web parasite spiders that grabbed a sneaky meal caught by the big female, and sometimes even consumed web. You can read more about them in this post from October 2012.

We've had some good spider activity at our house this year. Early this summer, I found the first Green Lynx spider that I had seen at our house. She was perched on top of a flowering milkweed plant. I was away a lot during the summer and didn't pay much attention to her again until fall when I spied her with a Monarch Butterfly that she had snagged for a meal. Lynx spiders don't catch food with webs, but instead position themselves atop flowers and wait for unsuspecting pollinators to get just a little too close, and...pow! At first I was shocked and a little sad that the Monarch had become prey in our garden, but I watched her lay eggs and knew she did get a chance to pass on her DNA to the next generation. A few days later, I found the spider with another large meal, a Monarch caterpillar. But once again, I wasn't too sad because the milkweed bush was loaded with caterpillars, and if they all survived they would have run out of food. I mentioned this my previous blog, but I think it is important to see Monarchs as part of a bigger ecosystem and not protect them at the expense of their predators who depend on them for food.
Green Lynx spider on milkweed early this summer

She caught a big Monarch butterfly for dinner. Notice her big abdomen--filled with eggs

Another big meal for a hungry spider

A few days later, the Lynx spider was missing. I thought she'd become food herself, caught by a bird or squirrel. But then I noticed her on top of a different bush where she could be even more stealthy. Truth is, the Monarch caterpillars were quickly defoliating the milkweed, so it was a smart move on her part. And just in time, too, because a few days after that I found her again, looking much thinner and clutching a huge egg sac. She tended the sac for several weeks. Then one day I checked on her and she was gone, but the eggs had hatched and dozens of tiny spiderlings clung to the remnants of the sac. I read that after about 2 weeks, the spiderlings would shoot strings of web into the wind (this is called "ballooning") and would be carried off to new locations to begin their adult lives. The cycle of life.

New perch with more shelter

Holding her egg sac. Note small abdomen.

View of the egg sac from below

Spiderlings

Spiderlings cluster around the egg sac. Click here for a video of the spiderlings wiggling.

Also active this time of year are the Argiope or Garden Orbweaver spiders. We have a couple of varieties here in Georgia. The Black and Yellow, or Zipper, or Writing spider and the Banded Garden Orbweaver. They make huge webs in perfect orbs and often decorate them with little lacy segments, call the "stablimentum". The purpose of the stablimentum is not exactly clear. The spiders may hide behind the screen they create, or it may alert birds to the presence of the web so they don't fly through. These spiders often perch in the center of the web and jiggle it back and forth and the stablimentum may attract prey to the web. Whatever the purpose, the effect is very interesting. Some spiders make more of a zigzag in their web, thus the name "Zipper Spider". They are fierce predators and you will often find a large grasshopper or butterfly wrapped up in silk in the web. In September I found a bundle in a Garden Orbweaver web and was a little afraid that it was a hummingbird. After looking more closely, I think it was a large moth. But a spider's gotta eat, too, right? A few weeks later I was in the right place and time to see a Banded Garden Orbweaver nab a grasshopper. I never realized how quickly they can immobilize and wrap their prey. Their spinnerettes can produce sheets of silk when they need it, rather than just one strand. It was fascinating. Many of the female spiders at this time of year are eating for more than one, with their huge, egg-filled abdomens. Argiope spiders make an egg sac that resembles a balloon.

Black and Yellow Argiope spider with zig zag stablimentum

Black and Yellow Argiope behind stablimentum. Hiding from prey?

This one caught a big moth

This Banded Argiope spider caught a grasshopper. Note the fancy striped legs.

Argiope spider egg sac

I mentioned the Golden Silk Orbeaver (Nephila clavipes) spiders found in Florida. I hadn't seen any up here in North Georgia yet. But recently I read reports from our natural history museum that some had been spotted up this way, along with a related spider from Asia, called the Jorō Spider (Nephila clavata). The first reports of this spider in North America have been here in Georgia. They're quite large and very pretty and I hoped to see one some day. Well, my wish came true this fall, and I found one, all right--in my own yard! As I have talked to people about this it has become clear that they are very widespread now and many of my friends have seen them, too. I have been watching this one grow from a smallish, skinny spider to a magnificent beast with an ever growing web. She seems to mostly catch bees, but one day I startled a Brown Headed Nuthatch and it flew into the web and became stuck. Here is a link to a video of the encounter on my photo website. I helped it out and have been checking the web for birds every day since then. So far there have been no other bird snags. I was tempted to remove the web and kill the spider because she is a potentially invasive exotic. But I really hate to do that. They're beautiful animals, just doing what they need to survive. I have not heard yet whether people consider them a problem, and I'm not sure how much good it would do to kill just one, anyway. Meanwhile, I'll keep watching the web and will hope for the best. And we'll see what spiders appear in the garden next spring. 

Jorō spider in her web

Brown-headed Nuthatch caught (for a moment) in a spider web