Black and Yellow Garden Spiders, Are They Harmful?

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In late summer – early fall it’s not unusual to find what is commonly known as the black and yellow garden spiders in your garden.  Some call it a Writing Spider.

This is because of the obvious zig-zag stitch always found the in the center of their awesome web.

Are the black and yellow garden spiders safe to have around?  What is her purpose?

Black and Yellow Garden Spiders, Are They Harmful?

I agree when you first come in contact with black and yellow garden spiders in your backyard garden, it is shocking.  Are writing spiders harmful to humans? The good news is they are completely harmless.

Black and Yellow Garden Spiders Female garden spider with her egg sac

When you see them on their web, you will find them sitting up-side-down with their head closer to the ground.  This is actually a defense mechanism for the black and yellow garden spider to be able to run and hide when they feel threatened.

Black and Yellow Garden Spiders On her web facing toward as a means of protection
Black and Yellow Garden Spider sitting up-side-down on web

The awesome web is attached to the ground at some point and this is the evacuation route to safety when they are startled or scared. They will actually sometimes, just drop immediately to the ground to take cover.

Garden spiders can bite if they feel threatened though.  It is said to be compared to a bee sting, but the bite is harmless.  They most often will choose to run from humans and other predators.

How Big Do Black and Yellow Garden Spiders Get?

Males and females differ from each other quite a bit.  In a female, the abdomen is black with symmetrical patches of yellow.

Her legs are a 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 the size of a quarter.  Female garden spiders actually can grow to four times the size of a male.

Black and Yellow Garden Spiders
Female Garden Spider Sitting on Spider Web

Male garden spiders are a couple shades lighter in color and much smaller than the female.

Habitat and Diet of the Garden Spider

Garden Spiders feed on flies, bees, aphids and other flying insects that get caught in their web.  She can spin a web over night.

It is circular in shape and contains a highly visible zigzagging X, called the stabilimentum, shape in the center.  It is not really know specifically why the zig-zag 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 in porch overhangs, from tree to tree, and other outdoor places.  Black and yellow garden spiders are most often found in backyard gardens, parks and wooded areas.  Their webs are normally about knee high or above off the ground.

The Garden Spider Egg Sac

The male spider seeks out the female in the web and after mating he dies.  She creates a brownish-paper-looking sac that will contain an average of 50-100 eggs inside.

The babies actually hatch in the fall and remain in the sac and lay dormant until spring when they emerge.  So protecting her and her babies is good for your garden.  If you see one of these spiders or her egg sac – DO NOT DISTURB!

Black and Yellow Garden Spider with egg sac
Garden Spider Protecting Her Egg Sac

Life Span of the Black and Yellow Garden Spider

As I’ve already mentioned, males normally die after mating with the female.  She, on the other hand, can live for several years if she is in a climate that does not have a cold winter.

Since black and yellow garden spiders are found from Canada down into the southern United States.  In regions where frost and cold temperatures occur, she normally dies during the first frost.

So she most often dies before she ever gets to meet her babies in the spring.

We have 7 living in our garden now.  I’ve known they were there and have been careful when picking the last of the tomatoes and bell peppers.  I’m hoping they move on before fall clean-up time.  

I have found 4 egg sacs  so far.  When I do fall clean up in a couple weeks, I’ll be careful not to disturb.  I will leave the web until after frost and I don’t see her anymore.  I will then gently place her egg sac, attached to the plant, in a safe place to over winter in the garden.

It is sad to know that winter is coming and they are doing their best to survive.  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 and admire their hard work and to watch them spin their prey they catch in their webs for food.

If you are interested in learning how to identify various spiders and insects, I’d highly recommend the National Audubon Society Field Guide to Insects and Spiders.  I have it and can’t say enough good things about it.  I use it all the time.  Its full color and laid out in a way to clearly and easily identify insects and spiders.

Do you have garden spiders living in your garden?  Feel free to tell me all about them.


Black and Yellow Garden Spiders life span, web, what they eat

3 thoughts on “Black and Yellow Garden Spiders, Are They Harmful?

  • September 16, 2018 at 10:36 am

    We have had several of these spiders around our house in the past, but haven’t seen any this year. We always called them writing spiders due to the zigzag in the web. Thanks for the information!

    • September 16, 2018 at 12:50 pm

      Hi Cheryl,

      They are fantastic creatures for sure. I wonder why you don’t have any around your house? Maybe next year. They are great to have around.
      Enjoy your fall season,

  • October 3, 2017 at 7:24 pm

    Good info to know about spiders.


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