The Brown Widow spider (Latrodectus geometricus) is an invasive species established across the southern and western United States. Encountering this spider on your property raises questions about managing its presence. Understanding its characteristics, the actual threat it poses, and removal options provides the clarity needed to make an informed decision.
Identifying the Brown Widow
The Brown Widow is a small spider, with adult females measuring around 13 millimeters in length. Coloration varies widely, ranging from light tan to dark brown or black. Unlike the glossy black appearance of its relative, the Black Widow, the Brown Widow’s abdomen is often mottled and not shiny. Its most distinguishing feature is the hourglass shape on the underside of the abdomen, which is typically orange or yellowish-orange, differing from the Black Widow’s bright red hourglass.
The spider’s egg sac is another reliable identifier. Brown Widow egg sacs are spherical and have a unique, spiky, cotton-fluff-like appearance, often described as resembling a World War II sea mine. These sacs can contain up to 150 eggs and are commonly found in sheltered, secluded locations, such as under patio furniture, in buckets, or within entryways. The webs themselves are usually messy, irregular, and often found near the ground in dark, undisturbed areas.
Assessing the Threat Level
The Brown Widow is venomous, but it is less dangerous to humans than the Black Widow, despite some studies suggesting its venom is more potent by weight. The difference in risk stems from the quantity of venom injected during a bite, which is substantially smaller. This lower volume of injected neurotoxin means that severe systemic symptoms are rare.
Bites from a female Brown Widow typically result in a localized reaction. Symptoms usually include pain at the site of the bite and a small red mark or lesion. While moderate reactions involving local pain, minor swelling, and mild systemic effects like nausea have been reported, the severe, protracted symptoms of latrodectism seen with Black Widow bites are absent. The species is also timid and often retreats or plays dead rather than biting, which reduces the likelihood of envenomation.
Safe Removal Options
Since the species is not aggressive and poses a minor medical risk, removal methods can be chosen based on preference. For a lethal approach, crushing the spider with a shoe or a rolled newspaper is a direct and effective method. Applying a targeted insecticide spray can also be used, though it is often less effective than physical removal. Care must be taken to follow product instructions for safe use.
For non-lethal removal, a vacuum cleaner with a hose attachment provides a safe way to capture the spider and its egg sacs from a distance. Dispose of the contents, including the spiky egg sacs, far from the home or seal them in a plastic bag to prevent hatching. When clearing webs from secluded areas like under patio furniture or woodpiles, wearing gloves and long sleeves is a sensible precaution. If dealing with a large number of spiders, contacting a pest control professional is the safest option.
Preventing Future Infestations
Reducing the available habitat is the most effective long-term strategy for discouraging Brown Widows. These spiders seek dark, protected spaces, so clearing clutter from garages, sheds, and outdoor areas removes their preferred hiding spots. This includes removing leaf litter, old woodpiles, and unused containers like buckets or nursery pots, which provide ideal shelter.
Storing items in sealed plastic containers instead of cardboard boxes eliminates potential indoor hiding places. Sealing any cracks, gaps, or holes around the foundation, windows, and doors of the home also helps prevent entry. Regularly sweeping down webs in corners and under eaves removes their structures and disrupts their ability to establish a presence.