Halloween decoration is in full swing. Ghosts, witches, and spiders are popping up everywhere. The prairies of Kankakee Sands seem decorated for the upcoming holiday too. All around are spider webs that glitter with the dew on these chilly fall mornings.
The most common spider that I see at Kankakee Sands during the months of September and October is Argiope aurantia, otherwise known as yellow and black garden spider, corn spider, zipper spider, writing spider, or black and yellow argiope.
Yellow and black gardens spiders are orb weavers, making the characteristic circular, spider-shaped webs that hang vertically from plant stems. The webs can be as large as two feet in diameter! A zig-zag band that runs down of the center of the web is a tale-tale sign that you are looking at a yellow and black garden spider’s web.
Females are often found resting head-down in the center of the web. She has a silver haired head, a yellow and black patterned swollen abdomen, and eight black and orange striped legs. Add it all together and you have a two-inch long female spider! Despite having seen hundreds of yellow and black garden spiders during my time at Kankakee Sands, I still regularly jump at the site of them. (They are indeed large, yet they are harmless to humans.) The males are much smaller than the females. At only one fourth to one half inch in length, the light brown males are easily and often overlooked.
Male and female garden spiders mate in the spring. During the summer months, the female will produce somewhere between one to four egg cases, each containing approximately 1,000 spider eggs. Her egg cases are tan in color, papery thin, and approximately one inch in diameter. She will attach the egg sac to her web and watch over it until she dies with the first frost, or by predation by a perhaps a bird, wasp, lizard or shrew.
The spider eggs within the egg sack will hatch in the fall of the year that they were laid. The tiny spiders will remain within the protection of the egg case during the fall and winter, emerging the following spring to begin making webs and eating insects.
Garden spiders are extremely common in sunny locations. They can be found in savannas, grasslands, prairies, open forests, marshes and swamps in southern Canada, the continental United States, Mexico and much of central America. They are regularly observed in gardens and grassy areas near homes, where food, such as grasshoppers, aphids, bees, wasps and flies are abundant.
Don’t like spiders near or in your home? I wasn’t too sure either until I read that a single spider is capable of consuming up to 2,000 insects in a year, including many of the insects that we consider agricultural pests, like grasshoppers, aphids, and even caterpillars. My line of thinking has changed so dramatically, that now when I see a spider web or cobweb inside the house, I think of the web as “spider habitat,” helping to keep our home pest free!
Garden spiders are known to have “site fidelity.” Once a garden spider finds a good location, it is apt to stay there for the duration of its life. There is a particularly large garden spider that makes her web on the edge of the prairie dock bed at the Kankakee Sands nursery. I enjoy seeing her each morning on her web. Her webs are in mint condition in the morning, but by mid-day they are a tangled grave of grasshoppers, mosquitoes and flies. Though I haven’t witnessed it myself, I’ve read that garden spiders consume their webs each evening and build a new one for the following day. I’m half tempted to sleep out one evening to find out for myself if that fact is true.
Come on out to Kankakee Sands this October and enjoy a Halloween hike on the prairie. Thanks to the yellow and black garden spiders, we are all decorated up and ready for the holiday!
The Nature Conservancy’s Kankakee Sands is an 8,300-acre prairie and savanna habitat in Northwest Indiana, open every day of the year for public enjoyment. For more information about Kankakee Sands, visit www.nature.org/KankakeeSands or call the office at 219-285-2184.