All About the Huge, But Beneficial, Garden Spider
The spider in this photo is huge, even scary to some. But not to worry, it doesn't kill dogs or cats or people. (It doesn't eat squirrels, either, though I wouldn't mind another ally to keep them out of my bird feeders.) This is the female garden spider (Argiope aurantia), a common sight in gardens where she likes to build her web. She's been lurking among your plants since spring, eating and growing as she goes. You didn't notice her until you walked out with your morning coffee one day in late summer or fall and came face-to-face with a fearsome-looking monster stretched out in a large web and looking hungry.
How to Recognize a Garden Spider
She's BIG. Decorated with striking yellow and black markings, the female garden spider's abdomen can be more than an inch long. Her legs extend twice that distance and are black with red or yellow bands. Male spiders are much smaller, ranging from a less conspicuous 1/4-to-3/8 of an inch long. They spend much of their time roaming around and looking for a mate.
The garden spider is an orb weaver, meaning it builds spiral, wheel-shaped webs. She builds her web by attaching four of five silk anchor lines to a central point and then adding a spiral of silk between them. The web's most distinctive feature is the stabilimentum – zigzags of silk above and below the center. The zigzags look a bit like writing, which is why this arachnid is also called the writing spider. Some think its purpose is to keep birds from flying through and destroying the web. It may also serve to strengthen the web and camouflage the spider as it waits for prey.
The web has another purpose besides snagging insect prey—it often holds a large egg sac up to an inch in diameter with as many as a thousand eggs inside. In warm-weather climates, tiny spiderlings emerge in fall. Where winters are cold, the eggs hatch in spring. Mama guards the egg sac as long as she can, but dies with the first hard frost.
Benefits of the Garden Spider
Though you might be disappointed to see your resident garden spider attacking bees and butterflies, this mostly daytime predator does benefit the garden, capturing the aphids, flies, grasshoppers, and mosquitoes that plague plants and people.
Its appearance may belie the truth, but this is not the demonic, screeching spider chasing people down that freaked you out in the movie Arachnophobia. Garden spiders aren't aggressive nor are they prone to bite unless threatened or trapped. Even if they were, their venom is harmless to people and pets. Of course, with any spider bite it's wise to keep an eye out for signs of an allergic reaction or infection and to contact a doctor if you have concerns.
How to Relocate a Garden Spider
Garden spiders have been known to take up residence in an inconvenient spot, stretching a web several feet wide across a pathway or stairsteps. If you're an arachnophobe, you may prefer to have that web completely out of sight. To move the spider, you can don garden gloves and use a plastic cup and a piece of cardboard to trap her. Hold the cup in front of her and quickly clap the cup behind. Release the spider onto a low-hanging plant in a more suitable area. If you're not feeling that brave, try the no-contact method, gently breaking the web with a broom or other long-handled tool. Eventually, the spider will give up and find another home.