Big, bold and beautiful, you can’t help but notice Black and Yellow Garden Spiders and their striking webs. They seem to appear like magic in late summer and fall. Have you ever wondered about them and where they’ve come from?
They may be called something different in your area: Corn Spider, Zipper Spider, Writing Spider (because of the design in the center of its webs), Golden Garden Spider, Yellow Spider or McKinley Spider.Entomologists know them by their Latin name Argiope aurantia (AR-ghee [or jee]-OH-pee; ah-DRAN-cha).
They belong to the order Araneae (ar-RAIN-ee-eye or ee) and the family Araneidae (AIR-uh-NEE-uh-die or ee). A fossil found in China of an extinct species, Argiope furva, shows that this genus dates back to at least 15.97 to 11.608 million years ago (Miocene Epoch). Because their web is so distinctive — large, spiral and wheel-shaped — Argiopes are in a group called orb-weavers. Many of them sport bright colors.
Black and Yellow Garden Spiders aren’t dangerous. To repeat, they aren’t dangerous! They aren’t aggressive. And, they don’t bite, unless severely provoked — leave them alone and they’ll return the favor. If forced to bite, their venom is harmless to humans and the pain is comparable to a bee’s sting.
They seem to go from non-existent to full-grown overnight, don’t they? Really, though, they’re with us all season long; we just don’t take notice of them until they’re large enough to catch our attention. They began back in the spring, as tiny spiders that constructed tiny webs. They’re now all grown up.
We generally notice Black and Yellow Garden Spiders because, well, they’re in our gardens. But, they aren’t restricted to that. You might also find them in other sunny places, such as tall grasses, shrubs or attached to structures. They’re uncommon in parts of the Rocky Mountains and the Great Basin, where there’s little vegetation. But, otherwise, they’re found throughout most of the continental U.S., Hawaii, southern Canada, Mexico and Central America.
There are three other Argiope species inhabiting North America, plus one in Hawaii. Around the world there are 3,500 species — all are rather large, have colorful abdomens and construct webs made of white silk.
The Black and Yellow Garden Spiders that catch our attention are all females. Like with many other spider species, the males are tiny by comparison. Not including their legs, males are only 0.20 to 0.35-inch (5 to 9 mm) long, while females are 0.75 to 1.10 inches (19 to 28 mm) long.
The Black and Yellow Garden Spider’s Latin name, Argiope aurantia, means “gilded silver-face.” This seems fitting, as most (not all) do have silvery hairs covering the front part of their body and a yellow (gilded) and black abdominal pattern. Their legs are black with red or yellow markings. (If a young spider loses a leg, it can be regenerated!) Each foot has three claws (most spiders have two). Their third claw is used to help handle threads as they spin their webs. Their bite is venomous and immobilizes their prey (not humans, though).
Their vision is poor. They have eight eyes, but instead of using eyesight they sense vibration and air currents to tell them about their environment. Spiders don’t have ears, but recent research involving a family of spiders called “jumping spiders” has shown that the hairs on their legs are so sensitive they can detect sound from several feet away — it’s likely that other spiders, perhaps Argiopes, too, can “hear” in this way. They also can smell and taste through sensory hairs on their legs and other parts of their body.
Black and Yellow Garden Spider eggs hatch in late summer or fall. The hatchlings look like tiny adults, except they lack mature reproductive organs. They become dormant and stay within their egg sac until the following spring. They’re tiny when they leave it. but grow ever larger through the summer, shedding their exoskeleton (molting) several times to make way for their growing bodies. By late summer and fall, they’re now a year old, fully grown and sexually mature. That’s when we begin to notice them. They’ll mate, lay eggs and the cycle begins again.
Female Black and Yellow Garden Spiders tend to stay in the same place throughout their lives. They’ll relocate their webs if they aren’t catching enough insects or they’re repeatedly disturbed. Males, on the other hand, roam around until they find a female. When they do, they usually construct a web nearby and begin courting. To communicate, the male plucks and vibrates the female’s web. (Males usually have a drop line ready when they approach females — occasionally, a hungry female will eat her mate!)
After mating, the female constructs one or more silken, roundish, brown-colored egg sacs, which look like cocoons. She attaches the sac(s) to one side of her web and keeps careful watch over them. Up to one inch (25 mm) in diameter, each sac may hold from 300 to more than a thousand eggs.
A female’s web may be up to two feet across. She hangs head down in the center to await prey, holding her legs together in pairs, so it often looks like she has only four legs, while in fact there are eight. She may also await prey from the edge of her web.
Below is an animation showing how a web is generally built. In the case of Black and Yellow Garden Spiders, a final touch is added — the zig-zag pattern in the center, called a stabilimentum. Scientists don’t know why they do it, but surmise that it attracts prey, provides stability or possibly warns birds away. Another interesting thing about the web: The entire circular part of the web (seldom the radial framework) is eaten at night and rebuilt.
In temperate climates, female Black and Yellow Garden Spiders live from their hatching in the fall to the first hard frost the following year. Males die after mating within their first year. In warmer climates, females may live for several years.
Prey and predators
For food, Black and Yellow Garden Spiders feed on virtually any insect (it’s usually a flying one) that gets caught in their web. They’re preyed on by birds, lizards, wasps, shrews, and others. They defend themselves from predators by first vigorously vibrating their web — this may make it harder for predators to home in on them. If that fails, they drop to the ground and hide. Their egg sacs are also preyed on.
Here are three more of the large Argiope species found in North America. Keep an eye out for them!
*Top photo: (Deisy Mendoza / Wiki; cc by 3.0)