Spider Webs in the Garden

Autumn is the time of the year when playful folks install synthetic webs in the corners and doorways of their homes. All other times, the genuine webs and their spiders are removed from the nooks and crannies of our homes with dusters and vacuum cleaners. You may wonder why spiders make webs.

Although both are arthropods, unlike insects with six legs and three main body portions, spiders have eight legs and two main body parts, the cephalothorax and abdomen. They are in the class Arachnida. Spiders produce protein-based silken strands from spinnerets on their abdomen. In Greek mythology, Arachne was an accomplished spinner who was turned into a spider. What the spiders do with these strands of silk varies. There are four types of spider webs: orb webs, sheet webs, funnel webs, and cobwebs, sometimes called tangle webs. But why does a spider make a web? A spider web extends the spider's sensory network. A web helps the spider detect and catch prey in the environment away from the spider's body.

A favorite children’s story, Charlotte’s Web, is about a spider web and the power of suggestion. One of the main characters, a barn spider named Charlotte A. Cavatica, created beautiful orb webs at the entrance to the barn where she lived. In this E. B. White novel, Charlotte spoke with the barnyard animals and could write words in her web for humans to read. Have you ever seen words in spiderwebs? Probably not, but you might have seen stabilimenta, the extra zig-zags of silk near the center of an orb-weaver’s web. These stabilimenta can be reinforcements to stabilize the web and act as visual cues to prevent birds from damaging it as they fly nearby. In its classic orb web, you might not notice a drab brown barn spider (Araneus cavaticus). Still, you might meet the barn spider's cousin, Argiope aurantia, a beautiful yellow and black orb weaver in your garden. I always have one in my flower beds. Like Charlotte, my orb weaver in the Araneidae family often replaces her beautiful web overnight.

Spider webs contain both sticky and nonstick threads of silk. The spiders know which strands are safe for them to walk on. Their prey, usually insects, are easily trapped by the sticky threads. As the entangled prey thrashes, the spider dashes to further wrap it in silk, ensuring the delicious meal does not escape or further damage the web.

Among the cobweb spinners are the cellar spiders of the family Pholcidae, with exceptionally long and narrow bodies and legs. In my childhood, when these ventured from my father's workshop to my mother's realm of the kitchen or living room, she managed them with a dry mop or the vacuum cleaner's hose. The cobwebs, spiders, egg sacs, and spiderlings were instantly gone. They are commonly found under decks, too.

Did you know that about half of spiders create webs not for capturing prey? These spiders construct webs as their hiding places. The shy spiders often are active hunting spiders that pop out to capture their prey, then retire to their den for safety.

Sheet webs of the Linyphiid spiders in shrubs, barns, and garages are expected. I manage the ones near the nightlights in my garage with a shop vac. In Columbia County, I often receive garden hotline questions about the spiderwebs in the shrubbery. The clients do not realize that these web-spinning spiders feed on the insects in the shrubs. Usually, there is a porch light or a living room light near a window that serves as an attraction to the insects. Spiders sense that the low-light location will provide a good meal.

On mornings when the dew is heavy, the funnel webs of grass spiders of the family Agelenidae are visible. These are modified sheet webs. The webs are always present in our lawns, just unnoticed at other times. In barns and sheds, dust may coat the webs of barn funnel weavers. The webs do not serve to entrap or entangle the prey, as there are no sticky strands. But when prey is sensed, the spider darts into action. These spiders are patient but active hunters.

Perhaps you've seen the brightly colored crab spiders of the family Thomisidae lurking among the petals in your flower gardens. These are among the spiders that do not spin webs at all. These ambush spiders have two pairs of elongated front legs to capture their prey. Rather than actively hunting, crab spiders wait for their future meals to visit the flowers. Crab spiders do not wrap their prey with silk. Female crab spiders occasionally stretch a silken line as a safety line or for males to follow.

I must mention another arachnid often mistaken for a spider, the daddy-long-legs. Also called harvestmen, they are not spiders but are in the related class Opilionidae. They are scavengers who gracefully tiptoe over decaying organic matter, squat down, feed upon it, and tiptoe away. While creepy-looking with their long, stilt-like legs and round pill-shaped bodies, they cannot produce silk, nor do they produce any venom at all.

So, as you view the web décor this fall, please do your best to find and admire the natural, spider-made webs in our environment, indoors and out.