In my previous post, I described a few changes in the local wildlife that serve as markers for the transition from Summer to Fall. I neglected to mention one of my favorite declarers of impending Autumn: Argiope aurantia, commonly called the Writing Spider or the Black and Yellow Garden Spider.
I began to notice some smaller specimens setting up shop among my tomato plants about a month ago. But this is the first sizable spider I’ve seen. She is probably not quite full grown, but she’s getting there. She erected her web among the tall blooming stalks of Cardinal Flowers that share space with Pitcher Plants in pots immersed in my front garden water feature.
It’s a perfect spot for a hungry spider. Unwary local pollinators drawn to the ruby throats of the Cardinal Flowers make easy prey for the quick reflexes of this predator. She is building up her reserves before creating her egg sac, which will protect hordes of tiny spiderlings until spring sunshine calls them forth.
I know this is a female because of her appearance, and the fact that males roam about in search of females; they don’t build webs. When they find a potential mate, they court her by plucking the strings of her web, sending vibrations through the gossamer threads that entice her toward him. After mating, the male usually dies, and the females eat their bodies. Unlike their Black Widow Spider sisters or female Praying Mantises, Writing Spider females do not actively kill their lovers; they merely don’t let a good meal go to waste.
Writing Spiders are so named for the squiggly zigzag of silk in the center of the web (a stabilimentum, technically speaking). Scientists have several theories about the purpose of this structure. Some think it attracts prey. Others think it makes the web more visible to those who might unintentionally walk through it. I know in my yard when I approach a Writing Spider’s web I haven’t seen, my first clue is usually when the occupant begins strongly vibrating the web, and the first thing I notice is usually that zigzagging bit of silk in the center. But just because it prevents me from walking through the web doesn’t mean that’s what her “writing” is there for.
Maybe the scientists haven’t yet stumbled upon the real reason for the Writing Spider’s silken signal. Perhaps she is conveying a message from Autumn, letting us know that the time for summer frolicking is nearly done. Leaf raking, pumpkin carving, and turkey stuffing will accompany crisper air, bluer skies, and the bedding down of flora and fauna for another winter’s sleep.