More and more of our clients are becoming concerned about the brown widow spider. How toxic is their venom and what can we do to control them?

Brown widow spiders are becoming more widespread throughout the southern regions of the US, from California to Florida, and even up to Ohio and Michigan. Their coloration varies from light tan to dark brown, with variable markings of black, white, yellow, orange, or brown on the back of their abdomens. Their spiky tan colored egg sacs are more easily recognizable compared to the smooth white to tan surface of most other spider egg sacs. The brown widow’s venom is twice as potent as that of the black widow. However, brown widows do not inject as much venom as the black widow and are less likely to bite since they are more timid.

Brown widows primarily nest outdoors on the undersides of patio and lawn furniture, playground equipment, garbage bins, and other structures and items that offered horizontal support and underside access, according to a recent study completed by Dr. Richard Vetter from University of California, Riverside. Only on rare occasions, brown widow spiders were found in garages or sheds, usually if the door was left open for easy access.

Sanitation such as the regular maintenance of outdoor items, reducing clutter in storage areas, and disposal of debris and piled materials around the exterior of a structure will aid in reducing brown widow habitats. Exterior perimeter treatments may aid in preventing the spiders from entering a structure, but it is best to inject pesticide dusts or aerosols into holes and crevices where the spiders are likely to reside.