Black Widow

What it looks like

• Glossy jet-black body, almost shiny
• Bright red hourglass marking on the underside of the abdomen
• Bulbous round abdomen on the female
• Tangled, irregular web with a thicker silk retreat

Where you'll find it

• Detached garages, sheds, barns, and outbuildings
• Woodpiles, brush piles, and stacked materials
• Crawl spaces and undisturbed corners of basements
• Rarely found in main living areas of Iowa homes

Behavior & biology

Black widows are reclusive — they build a tangled web in a sheltered spot and rarely leave it. Females are venomous; males are tiny and harmless. The female sometimes (not always) eats the male after mating, hence the name. In Iowa, populations are small and scattered. Most encounters are in sheds, barns, and woodpiles.

Iowa activity calendar

Signs of an infestation

• A tangled, sticky web in a corner with a small silk retreat
• Round white egg sacs (about 1/2" diameter) hanging in the web
• The spider itself — almost always seen at night near the retreat

Health & property risk

Black widow venom is a neurotoxin. Bites cause severe muscle pain, cramping (often in the abdomen), sweating, and elevated blood pressure. Healthy adults usually recover with supportive care; children, elderly, and people with heart conditions should be evaluated immediately. Antivenom exists but is rarely needed.

How we treat it

1. 1

   Locate + remove webs and egg sacs

   We physically remove all webs and egg sacs we find. Egg sacs left behind hatch hundreds of spiderlings.

2. 2

   Direct treatment

   We apply residual insecticide to harborage areas — corners of sheds, woodpiles, foundation gaps, and crawl spaces.

3. 3

   Prevent re-establishment

   We point out the clutter, lighting, and prey insect populations that attract widows back.

Why DIY usually fails

Physically removing the web and egg sac is effective if you can identify the spider safely. Wear gloves, use a long stick, and double-bag everything before disposal.

FAQ