Black And Yellow Spiders: What Type of Spider Is That?
Identifying Black and Yellow Spiders
Spiders come in all shapes and colors and sizes. It is the ones with the bright colors and large sizes that both frighten and fascinate us. In a previous post I talked about identifying brown spiders, so I thought it only fitting that I do a post on black and yellow spiders, which are commonly found in the Eastern United States.
First, a disclaimer, I'm not a spider expert, but I am a naturalist who has had years of experience in the field. This is by no means a complete picture of all of the yellow and black spiders out there, just a snapshot of the most common ones. None of these spiders are harmful to people, but they can and will bite when frightened, like all animals or insects. However, their presence and job as insect eaters far outweighs the possibility of being bitten by these harmless spiders.
The black and yellow spiders that you are most likely see are (in alphabetical order):
Arrow-head orb weaver (Verrucosa arenata)
Arrow-head orb weavers have a pointed and arrow shaped abdomen, and belong to a very large family of spiders found in North America. They can be about 1/2" long with a triangular shield on their back that is usually yellow-white to orange. Their legs can appear orange with black striping. Unlike other spiders, these like to sit with their heads facing "up" on the web, while other spiders like to have their head facing down. They are usually found in forests and woodlands around moist and damp areas.
Arrow-shaped micrathena (Micrathena sagittata)
The Arrow-shaped micrathena (my-kruh-thee-nuh) is one that you will most likely meet on a trail or hiking through the woods (if you're like me you've face-planted a share of their webs while hiking undisturbed trails). They have elongated spikes on their abdomen and they can grow to be 1/2" to 1" long. The female is usually dark red-brown and her abdomen is yellow on the shield. The spikes are usually brownish-black on the tips. The males don't have spines like the females do. Here's a great website with more pictures.
Black and yellow garden spider (Agriope aurantia)
The black and yellow garden spider is the most commonly seen of black and yellow spiders. It can grow to be quite large (bodies of about 1/2" to 1" long, but their legs can stretch up to fist size) and they are commonly found around homes and in gardens. Garden spiders are also called the yellow garden spider, writing spider, or Agriope (which for fans of Harry Potter sounds close to Arigog). They like to build near open grassy areas or fields, and along garden edges. Their webs are circular and can get up to 2 ft wide. There is usually a stabilimentum (or supporting zig-zag) of silk in the center of the web. It's thought that it's also used for reflecting UV light to lure insects or to warn off flying creatures like birds. They can be big, but they're harmless.
Marbled orb weaver (Araneus marmoreus)
The orb weaver family is quite large, but the marbled orb weaver is a standout because of its beautiful yellow-orange and black colors. They can be found in trees, wooded areas, streams, grasses, and shrubs. The adults can be anywhere from 1/2" to 3/4" in size. Their abdomens are mostly orangish to yellow with orange looking legs striped with black or brown. I personally tend to notice them around the fall when the leaves are turning, for some reason they seem more common then and their colors and abdomens stand out more.
Spiny backed orb weaver (Gasteracantha cancriformis)
This type of spiny spider looks like a crab with its wide shielded back and spines. They are only about 1/4"-1/2" long, and are easy to miss in the yellows and greens of the forest. They are found in woodland edges and shrubs mostly. There's a wide variation in their spines and colors, from pale yellow-white and reddish spines to bright yellow and blackish spines. There are six points on their abdomen. The males lack the spines and are usually smaller. Both have black spots. I think this one looks like it has a skull/smiley face on it, most do. You can read more on this page from the entomology department at the University of Florida.
This list of spiders is by no means all of the black and yellow spiders out there, it's just a quick look at some of the most common ones you might encounter. Remember, they're not poisonous and they're incredibly beneficial to your garden and around your home. Leave them to help you out or relocate them to somewhere safer. Always try to keep them around, they're great neighbors!