Spider Control & Brown Recluse Guide

Dangerous Spiders in Missouri

Missouri sits in the heart of brown recluse territory, and the St. Louis metro area has one of the highest concentrations of brown recluse populations in the country. While most spiders found in homes are harmless, two species pose genuine medical risk.

Brown Recluse

Missouri’s most medically significant spider. Light brown with a distinctive violin-shaped marking on the cephalothorax. Unlike most spiders that have 8 eyes, the brown recluse has 6 eyes arranged in 3 pairs. They are shy, nocturnal, and prefer undisturbed areas: closets, boxes, behind furniture, inside wall voids, and storage areas. Bites typically occur when the spider is trapped against skin — putting on stored clothing, reaching into boxes, or rolling onto one in bed. Their venom can cause necrotic skin lesions that take weeks or months to heal.

Black Widow

Less common than brown recluse in the St. Louis area, but present. Jet black with a red hourglass marking on the abdomen. Found in garages, sheds, woodpiles, and dark undisturbed areas. Their venom is neurotoxic and can cause severe pain, muscle cramps, and in rare cases, serious systemic reactions.

Common House Spiders & Wolf Spiders

Most spiders you encounter indoors are harmless. Common house spiders build messy cobwebs in corners and basements. Wolf spiders are large, fast-moving ground hunters found in basements and garages. Their size is alarming, but they are not medically significant. However, their presence indicates a prey insect population in the home.

Signs of Spider Activity

• Webs accumulating in corners, basements, garages, and storage areas
• Regular spider sightings inside the home, especially in the evening
• Brown recluse sightings in closets, behind headboards, in stored boxes, or in shoes
• Egg sacs in undisturbed areas (attics, crawl spaces, closets)
• Increased insect activity — spiders follow their food source
• Unexplained bites that develop redness, swelling, or necrotic centers

How Roberts Controls Spiders

Our 3-Tier Brown Recluse Spider Management Program goes far beyond a standard perimeter spray. It is designed specifically for homes with confirmed or suspected brown recluse activity:

Tier 1 — Dust Application

We apply long-lasting insecticidal dust and silica-based dust (amorphous silica gel) into wall voids, behind outlet and switch plates, and into cracks and crevices throughout the home. Silica-based dust provides up to 10 years of residual activity in undisturbed voids — an exceptionally long-lasting barrier.

Tier 2 — Interior Spray

We apply professional-grade residual spray along baseboards, in closets, and in known harborage areas. Non-repellent chemistry that spiders contact and absorb through their feet.

Tier 3 — Exterior Perimeter

Foundation treatment and cobweb removal to reduce spider entry from outside. This is also maintained through our R.O.S. program. Every R.O.S. visit includes exterior cobweb removal for ongoing population control. Learn more about R.O.S. →

Brown Recluse Prevention

• Declutter — Reduce clutter in closets, basements, garages, and storage areas. Brown recluse thrive in undisturbed spaces.
• Seal cracks — Seal gaps around windows, doors, and utility penetrations.
• Use sticky traps — Install glue boards along baseboards in bedrooms and closets for monitoring. Catching even one brown recluse confirms a population.
• Shake out clothing — Always shake out shoes, gloves, and stored clothing before wearing them.
• Move beds from walls — Keep beds away from walls and bedding from touching the floor.
• Reduce outdoor lighting — Lights attract insects, which attract spiders. Switch to yellow or sodium vapor bulbs.