Black Widow Spider
Adult female black widow spider (Clemson University, Bugwood.org)
Immature female black widow (Joseph Berger, Bugwood.org)
Adult male black widow (Whitney Cranshaw, Colorado State University, Bugwood.org)
- adult female is shiny black with a red hourglass on the underside of the abdomen (there are beneficial lookalikes without the red hourglass)
- immature females have a pale brown to black body with white to orangish banding; they get progressively more solid black as they molt toward adulthood
- males are about 1/3 the size of females and are pale brown with white markings, resembling immature females
- prefer pre-existing holes in dark, undisturbed areas
- hide during the day and are in their cobwebs at night
- common around building foundations, rock piles, wood piles, outbuildings, water meter/irrigation boxes and around exterior lighting
- can be a serious health risk, especially to children and elderly people
- bite can cause pain, nausea, cramping or death (rare)
- Minimize nesting habitat around property.
- Seal exterior cracks and crevices to reduce hiding places.
- Regularly vacuum individuals and webs.
- Reduce clutter indoors and outdoors.
- Install tight-fitting door sweeps.
- Install tight-fitting screens in windows.
- Reduce other insects that serve as food.
- Change exterior lighting to sodium vapor bulbs.
IPM for Spiders: Integrated Pest Management in Sensitive Environments (University of Nebraska-Lincoln Extension)