Beware of the Brown Widow Spider
BYMIKE DONAHOE County Extension Director Santa Rosa County

Courtesy Photo Don't get bitten by one of these.

Few spiders are apt to cause as much fear as the black widow. The southern black widow is our most common and recognizable widow spider.

However, another species that has recently become established along the Gulf Coast is the brown widow, Latordectus geometricus. The brown widow is a widespread species found in the tropics. In the United States, it was introduced into south Florida.

In recent years, this spider has spread throughout Florida and it has been reported in coastal areas of Alabama, Mississippi, Louisiana, Georgia, Texas, and South Carolina. This summer large infestations of the spider were found in Santa Rosa County in the Milton area.

Brown widow spiders are generally lighter in color than the black widow. They vary from light tan to dark brown or almost black, with variable markings of black, white, yellow, orange, or brown on the back of their abdomens.

The underside of the abdomen has an orange or yellow-to-orange hourglass marking, as opposed to the red hourglass design on the black widow. It often has dark bands on its legs.

Another way to detect the presence of brown widows is by finding their egg sacks which are very different from those of the other widow spiders. The outside of the egg sack is covered with pointed projections that resemble a sandspur seed. It has also been described as spiky, tufted, or fluffy looking.

Like most spiders, the widow spiders are shy and will not bite unless aggravated. The brown widow is extremely timid; the only bites reported have resulted from a spider being accidentally trapped against the victim's body.

This usually occurs by putting on clothes with a spider inside or sticking one's hand in recessed areas or dark corners. According to Dr. G.B. Edwards, an arachnologist with the Florida State Collection of Arthropods in Gainesville, the brown widow's venom is twice as potent as black widow venom.

However, they do not inject as much venom as a black widow, are very timid, and do not defend their web.

Other authorities claim the brown widow produces clinical effects similar to that of the black widow but the typical symptoms and signs being milder and tending to be restricted to the bite site and surrounding tissue.

If you suspect that a widow spider has bitten you, capture the specimen for identification, if possible, and immediately consult a physician.

The brown widow most often builds its web in secluded, protected sites that have not been disturbed. Some typical sites include inside old tires, empty containers such as buckets and flowerpots, in crawl spaces, under chairs, porch railings and roof eves, and in piles of firewood.

Brown widows reproduce rapidly, and one female can produce up to 18 egg sacs. Once found, this spider is usually indicative of a widespread population which is extremely difficult, if not impossible, to eradicate.

Sanitation and elimination of nesting sites are the most important control strategies to reduce widow spider infestations around the home. Inside the home, spiders, their egg sacs, and webbing should be removed with a vacuum cleaner.

After vacuuming, the vacuum bag should be removed immediately and placed in a sealed plastic bag for disposal. As an added precaution, bags containing spiders and egg sacs can be placed in a chest freezer for several hours.

Outside the home, hiding places such as bricks, weeds, firewood, building materials, and other debris lying on the ground should be moved away form the building or disposed of.

Cracks, holes, and spaces around doors and windows should be sealed or fitted with weather stripping.

If spiders remain after sanitation work, insecticides may have to be used. Inside the home, space sprays containing pyrethrins or pyrethroids are effective in killing spiders.

Spot treatment with a residual insecticide to locations where spiders build their webs can be helpful to prevent new spiders from becoming established.

Chemical spray control of spiders is difficult outdoors because web spinning spiders do not tend to contact treated surfaces. Insecticidal dust can be more effective because the dust tends to cling to the spider webs for long periods.

When spiders chew their webs to recycle silk, they consume the toxicant and die. For more information on spider identification and control contact your local county Extension office.

Mike Donahoe is the County Extension Director for Santa Rosa County. The use of trade names, if used in this article, is solely for the purpose of providing specific information. It is not a guarantee, warranty, or endorsement of the product name(s) and does not signify that they are approved to the exclusion of others.

For additional information about all of the county Extension services and other articles of interest go to: http://www.santarosa. fl.gov/extension