[Spider Control] Managing the Black Widow Spider

Features - Spiders

Because these spiders are so reclusive, hidden away in dark corners and under objects, it’s easy to accidentally “disturb” them.


Editor’s Note: The following article was adapted from Techletter, a biweekly publication from Pinto & Associates, Mechanicsville, Md. To subscribe, visit www.techletter.com or call 301/884-3020.

The black widow spider may be our most recognizable pest. It’s found in every state except Alaska. Although there are other shiny black spiders and other similar “widow spiders,” it’s the red hourglass marking that identifies the female black widow.

The male spider and the young spiderlings are marked with red, orange and white. They’re small, inconspicuous and harmless. It’s the mature female whose bite can cause severe illness.

The black widow avoids light and is usually found in dry, undisturbed places outdoors such as in woodpiles, under stacked stones, boards or building materials, in boxes or crates, in trash piles or tree stumps, even in rodent burrows. Favorite places are in man-made outdoor structures such as outhouses, sheds, barns, chicken houses, and under porches, decks or eaves. Black widows may be encountered in outdoor meter boxes and even in rodent bait stations. Indoors, they can be found in crawlspaces and in undisturbed corners of basements or garages. Cold or drought may drive them into buildings.

Like other spiders, the black widow is not aggressive unless disturbed or when guarding her egg sac. But that’s the catch. Because she is so reclusive, hidden away in dark corners and under objects, it’s easy to accidentally “disturb” her.

The female black widow spins an irregularly shaped web with a small central tunnel. She stays in or near her web, usually hanging belly up with her hourglass marking showing. Hanging next to her may be a brown, papery, oval egg sac, about ½ inch long. In colder regions, the spiderlings overwinter after hatching, developing into mature adults the following spring.

Zenprox EC Approved for Control of Spider Infestations

Zenprox EC, a non-repellent contact kill product from the Zoëcon Professional Products division of Central Life Sciences, effectively controls a variety of more than 25 pests including cockroaches, fleas and bed bugs, the manufacturer reports. Most recently though, PMPs have been receiving positive reviews from customers regarding the use of Zenprox EC for the control of spiders.

“Customer feedback confirms that Zenprox EC is working extremely well on spider infestations,” said John Neberz, business manager, Zoëcon Professional Products division. “The rave reviews have been great, and we continue to communicate with customers to ensure that their pest control needs are being met.”

This broad-spectrum concentrate is approved for the control of the brown recluse, black widow and cellar spider species. Zenprox EC is designed for indoor use and can be applied as a broadcast, spot or crack and crevice treatment to a range of commercial and residential accounts including homes, hotels and warehouses. The active ingredient, Etofenprox, ensures quick knockdown and offers an extended residual, while controlling more than 25 different insects.

“Zenprox EC is performing extremely well on brown recluse, black widow and cellar spider infestations and we are proud to provide customers with a consistently effective product,” said Doug VanGundy, director of technical services.

Zenprox EC can be used by itself or as a tank-mix partner with an Insect Growth Regulator (IGR) such as Gentrol IGR or Precor IGR.

For more information on the full line of Zoëcon products and to read what customers are saying about Zenprox EC, visit www.zoecon.com.

Source: Central Life Sciences


There are periodic “outbreaks” of black widow spiders in more northern regions. Some years, the numbers are few, while the following year there may be large “blooms” of spiders, apparently due to weather conditions. In southern regions, black widow numbers remain fairly consistent from year to year.

Taming the Widow. The following control guidelines apply to most spider problems, including the black widow. The mechanical control measures can be undertaken by the PMP or the customer.

  • First, conduct a thorough inspection to locate spider harborage sites for cleanup or treatment. You’re more apt to find black widows at night when they position themselves in the center of their webs.
  • Whenever possible, change the conditions that are attractive to the spiders. In other words, reduce sheltered hiding places for the spiders and reduce the number of spider prey. Wear gloves and long sleeves when working in suspected spider harborage sites.
  • To keep spiders out of houses, move firewood and stone debris piles away from the foundation. Elevate these materials off the ground for storage.
  • Indoors, reduce clutter in garages and basements. Remove seldom used items such as cardboard boxes, old clothing, etc. Vacuum frequently using a crevice tool.
  • Small numbers of black widows are easily destroyed mechanically (without chemicals). Simply swat them with a flyswatter or other long-handled tool. Destroy webs and egg sacs by brushing, hosing or vacuuming.
  • Periodically use a garden hose and high pressure to wash down outside harborage areas such as rock piles, under decks and roof overhangs.
  • Reduce outdoor lights that attract spider prey.
  • Many residual insecticides are labeled for the control of spiders. Treat all harborage sites, especially dark corners. Wettable powders, suspensions, or microencapsulated formulations may provide a longer residual. Insecticide dusts tend to cling to the webs and work well in attics and crawlspaces. Do not treat woodpiles with residuals if the wood will be burned indoors.
  • There is an anti-toxin available for black widow bites. If bitten, get medical attention immediately.


Want To Learn More?

The PCT Media Group is pleased to announce the publication of the PCT Field Guide for The Management of Urban Spiders, 2nd Edition by Stoy A. Hedges and Richard S. Vetter.

Completely revised and updated, the 2nd edition Spider Field Guide is an essential educational resource for pest management professionals. The book was written to provide PMPs with a handy resource they can access from their service vehicles for practical, up-to-date information on these challenging pests. Topics covered in the field guide include:

  • Basic Spider Biology
  • Health Aspects of Spiders
  • Inspection Tips
  • Successful Treatment Strategies
  • Expanded Full-Color Photo ID Section

Hedges, director of technical services, Terminix, and Vetter, one of the country’s leading spider experts, provide a thorough review of the biology and behavior of spiders as well as an invaluable 24-page full-color photo identification guide.

“The biggest challenge for our service professionals is the identification of the spider involved and this guide was written with the service professional in the field in mind, so that they can solve the problem as quickly as possible,” Hedges said.

At $12.95 per copy, the 256-page field guide is value priced so PMPs can provide all of their technicians with their own copy (quantity discounts are available). For more information or to order visit www.pctonline.com/store or call the PCT store at 800/456-0707.