Black and Yellow Garden Spiders – Friend or Foe?

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In later summer, if you encounter a black and yellow garden spider in your garden, it can be startling. Are they poisonous? What is their purpose? Are they beneficial to the backyard garden? Read on to find answers to all these questions.

If you are lucky enough to accidentally run into a yellow garden spider, once the initial shock is passed, you should realize that it can be very beneficial to your garden.

This sensational creature has several common names, such as black and yellow argiope, corn spider, golden orb-weaver, writing spider, garden spider yellow, and zipper spider. They usually appear in late summer to early fall.

You’ll know it is a writing spider by the prominent zigzag stitch (stabilimenta) that is always found the in the center of her awesome web.

Every spring, they emerge from a tear-drop sac as tiny spiderlings. They will toss a strand of silk out into the air to catch winds to other locations. So they can appear in many places beyond the garden, wherever the wind takes them.

They grow all summer if they survive; we only notice them in the early fall once they are fully grown and obvious.

Are Garden Spiders Poisonous?

These spiders can bite if they feel threatened. You can compare it to a bee sting, but it is harmless to humans. 

Though not venomous to humans, it is to insects. More often than not, when you see one of these spiders, it will choose to retreat or run from you and other predators.

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But still, if you know nothing about them, the first encounter can be frightening. Educating yourself is the best way to overcome the fear of this spider. They have a purpose, and it’s a rather important one.

Most often, you see females rather than males, but again, both are harmless.

She will be sitting upside-down with her head closer to the ground. This is her defense mechanism to be able to run and hide if she feels threatened.

Her web is attached to the ground at some point; this is the evacuation route to safety when they are startled or scared. And sometimes, they will immediately drop to the ground to protect themself.

These garden spiders will not come after you; they want to get away to protect themselves.

Yellow Garden Spider Size

Males and females differ drastically from each other. Therefore, they are easy to tell apart, and neither of them poses a danger.

Females

• The abdomen is black with symmetrical patches of yellow.
• Her legs are reddish-brown at the base and black towards the tips. 
• She can grow up to about 1.5 inches in body length, and her abdomen can be about a quarter-sized. 

Males

• Male spiders grow to be 1/4 inch to 3/8 inch in size, much smaller than females.
• His body is silvery-gray to a plum color with yellow banded legs.

The male’s responsibility is to mate with the females and nothing more. He doesn’t spin webs and will often become the female first meal after mating.

Black & Yellow Spider Diet

Orb Weavers, another name for them, are effective garden predators. So they are a friend to the backyard garden. They benefit the garden by helping to control the insect population.

The females will spin a web overnight that catches flies, stinkbugs, aphids, grasshoppers, and other flying insects. Sadly, her web often catches bees and butterflies as well.

When these insects get caught in her web, she stings them with a venomous bite that paralyzes them, and she will then spin a web around them to save them as a meal.

Webs of The Garden Spider

It is circular and contains an obvious zigzagging X, called the stabilimentum, shape in the center. It is not known specifically why the zigzag exists, but it is speculated that it is for birds so they do not fly into the web and destroy the spiders’ hard work.

They can spin their webs on porch overhangs, tree to tree, and other outdoor places. In addition, black and yellow spider webs are often found in backyard gardens, parks, and wooded areas. Their web usually is about knee-high or so above the ground.

The Garden Spider Egg

The males seek out females in their web, and after mating, he dies. This is why it often becomes her first meal after successfully mating.

She will then create a tear-drop brown silk sac, about an inch in diameter, to house her eggs. Each sac can contain hundreds to even a thousand or more eggs inside it.

The spiderlings hatch in the fall but remain in the sac and lay dormant until spring. If the sac survives the winter temperatures and predators, the spiderlings will emerge in the spring.

Often this is not the case; the sac doesn’t survive. So protecting these cacoons is helpful for your garden. Therefore, if you see one of these spiders or her egg sac – DO NOT DISTURB! Sadly, she will die.

Moving an Egg Sac Safely

These spider sacs don’t always appear in the safest places. My first one was found on okra stalks in the garden, and once I started cleaning up for the winter, it was no longer safe.

A reader recently contacted me with a single sac on a potted pepper plant. She was concerned for its safety since living in Vermont, where winter temperatures get around -20 degrees F.

After having the conversation back and forth, we did decide to move the whole plant inside an open-ended hoop house she had on her property. The sac will be protected from the deep snow and extreme temperatures until spring.

To my knowledge, there is no proven way to move a sac safely. But sometimes, your best attempt can be necessary. Once she is no longer alive, carefully cut the stems the sac is attached to and move it to a safer area under a bush or as close to her chosen habitat as possible. This is no guarantee, but it’s worth a try.

Life Span of A Garden Spider

As I’ve already mentioned, males usually die after mating with a female. But on the other hand, she can live for several years in a climate that does not have cold winters and frost.

Since black and yellow garden spiders are found from Canada to the southern United States, most die during the first frost.

This year we have seven spiders living in the garden. I’ve known they were there and have been careful when harvesting the last of the tomatoes and bell peppers and doing fall cleanup.  

I’ve found four egg sacs so far. I’m doing my best not to disturb them. I will leave the web until after frost, and I don’t see the females anymore. Then I will gently remove the egg sacs attached to the plant stem to a safe place to overwinter in the garden.

It is sad to know that winter is coming, and they are doing their best to survive. However, I don’t think giving up a small space in the garden for them is too much to ask.

The weather is cooling, and it is enjoyable to go into the garden, admire their hard work, and watch them spin the prey they catch in their webs.

Suppose you are interested in learning how to identify various spiders and insects. In that case, a great book to add to your library is the National Audubon Society Field Guide to Insects and Spiders. It’s a very lovely full-color leather-covered book that is great for taking on nature walks and outdoors.

Even More Garden Pests:

• 15 Natural Ways to Get Rid of Tomato Hornworms
• How to Get Rid Of Ants in the Garden
• How to Kill Tomato Fruitworms
• How to Identify and Get Rid of Aphids
• How to Identify and Get Rid of Squash Bugs
• How to Get Rid of Squash Vine Borers
• How to Get Rid of Slugs in a Garden
• Get Rid of Earwigs and Protect Your Plants with These Simple Tricks

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