Master Weaver: Yellow Garden Spider

An itsy bitsy spider climbed onto the hose faucet handle just under my study window. A small brown and gray creature, he had most likely spent his life savings on one fling with a nearby lady, and now had little or no energy left. He fell to the ground when Bryan touched the faucet handle.

Meanwhile, the lady of his dreams hung in the center of her web waiting for something to happen. Her potential mate had climbed carefully onto her web and plucked its strands like a harp, sending a shiver of vibrations throughout her web. He was basically ringing her doorbell and announcing his intentions to court her. If she favored him, they would mate and then he would die. He came prepared for disappointment, though, with an escape route already planned out in case she rejected him. He is only about a third as big as his lady, so she’s pretty formidable.

Our yellow garden spider (Argiope aurantia) is an orb weaver. In a remarkable feat of engineering, she builds a complex and geometrically sound web with amazing tensile strength every morning. It only takes her about half an hour to complete.

She starts out by anchoring two strands of silk to points that will support the web. Then she builds a bridge between them and drops down from the center of the bridge to create a third anchor point. Now she has a vertical Y-shaped structure with the arms of the Y meeting in a central point. Next, she begins weaving around the arms of the Y, creating triangular spaces that support spokes running from the hub to the outside perimeter where she anchors them to vegetation. Now she has a frame made of non-sticky high tensile strength silk with a central hub and spokes radiating out from the center. Each element of the frame has been tested and adjusted using her legs to measure the spaces and gauge the tautness of each strand.

Now, working from the center to the outside, she creates a loose spiral that will hold everything in place while she gets ready for the last step. Using a different type of silk which is very elastic and coated with sticky stuff, she weaves a carefully spaced spiral from the outside to the inside of the web. The spacing of the spiral threads is optimized for the prey she is likely to capture in this space.

To make her web, our orb weaver has glands on her abdomen that produce various types of silk and glue needed for the web. She can control the thickness of the strands of silk she produces and also knows which ones to use where. For the framing elements, she uses a non-sticky silk with high tensile strength. She uses glue from a different gland to glue the elements of the frame together. Another type of silk which is highly elastic and coated in a sticky substance is what she uses for that final spiral that forms the capture part of her web. When she catches prey, she uses yet another type of silk to wrap her prey in to immobilize it.

The end result is a vertically positioned round web with a platform in the middle for the spider to rest on, 24 or more spokes leading from the center to the outside, and a broad circular region of the web that is ready to catch prey. She has also woven a white zigzag vertical feature into the web which may serve to make the web visible to birds so they won’t crash into or through it. It is nearly invisible otherwise. The spider hangs on the central platform head-down with her legs splayed waiting for company. Throughout the day, the web will most likely be damaged, and the sticky spiral will collect pollen and dust as well as insects. So she will probably build a new web tomorrow morning. She may eat the old web to preserve resources.

The Yellow Garden Spider stands head down and shows her underside. A structure of fine silk is prominent, extending downward from the center of the web. Called a stabilimentum, its purpose is the subject of debate. Contrary to its name, it doesn’t provide stability to the orb, being too weak and lightly attached to add significant strength. Author photo.

The female yellow garden spider is actually black with symmetrical yellow markings on her abdomen and black and yellow legs. Orb weavers like our yellow garden spider have three claws on each of eight feet whereas most spiders have only two claws per foot. The extra claw helps with constructing the web. Both males and females have gray heads and bodies covered in short hairs.

Yellow garden spiders are native to the New World and can be found in north and Central America. When they hatch, they are tiny spiderlings which will grow and molt several times before they attain their adult sizes. Parasitic wasps may lay their eggs in the spider’s Egg cases, and another sort of wasp may capture adult spiders, kill them and provide them as food for their own offspring. The spiders, on the other hand, will capture unwary insects in their webs, sting them, wrap them in silk and eat them when they’re dead. Their venom is lethal to small insects but harmless to people.

Our yellow garden spider has taken up residence under my study window and has stayed there for some weeks, weaving her web and keeping the insect population in the garden down. If she is lucky, she will stay there until the first hard frost. Her offspring will overwinter underground, emerging next spring, ready to start the cycle of life over again.

Photos by Author. A large black and yellow spider stands menacingly on the strands of her web attached to the red siding of the house. Yellow Garden Spider has been here for weeks, gathering resources to produce the next generation.