Widow Wars

The primary goal of this project is to document prey consumed by non-native brown widows and the three native black widow species across the United States. This information will be used to examine the potential impacts of brown widows on native species and to assess variation in diet between spiders living in urban and non-urban populations.

Both brown and black widows eat a wide variety of prey, from small insects to vertebrates such as lizards, snakes, and small mammals. Our primary focus is to understand the impacts of brown widows on other species. However, the diets of brown and black widows species in urban areas are not well characterized. We hope to resolve this problem through crowdsourcing—by asking people all across the United States to photograph prey items of brown and black widow spiders.

Brown widows are originally from Africa, but they have been widely introduced around the world. They are now found in California, Hawaii, and across many states in the southern United States. There are also three native black widow species across much of the United States—the western, southern, and northern black widows.

These widow species tend to build webs within a few feet of the ground, with numerous strong, sticky strands running from an upper support structure to the ground. To people, the webs appear disorganized, but to the spiders, the webs are built strategically to ensnare any potential prey walking through the area. In urban settings, these webs are often built along walls or fences or from objects near walls (like potted plants, BBQs, patio furniture, and trash bins). Widow webs can also be found in outside sheds and storage closets.

For this project, we ask participants to:

1) Find widow webs.

2) Document which species made the web by photographing the spider and/or any egg sacs. Brown widow egg sacs are spiky and look like a Medieval mace; black widow egg sacs are smooth, like little round cotton balls.

3) Document any prey items in the web or discarded prey items that are laying beneath the web (these are usually dry carcasses with some spider silk wrapped around them). Check back on inhabited webs every few days to document any new prey items.

4) Please submit observations labeled as the widow species (or just to the genus), with photos of the spider or eggs, and with photos of prey items all as a single observation. less ↑