The brown widow spider, Latrodectus geometricus, is becoming more common in various regions. This arachnid, a relative of the black widow, is expanding its presence, particularly in urban environments. Understanding its characteristics and behaviors is helpful for safe coexistence.
How to Identify Brown Widows
Brown widow spiders range in color from light tan to dark brown or nearly black. A distinguishing feature on the underside of their abdomen is an hourglass marking, which appears orange or yellow, unlike the bright red found on black widows. Their legs often display dark bands, with one half of each segment lighter than the other. Some individuals also have a row of white spots on their back or faint white stripes along their sides.
A unique identifier for the brown widow is its egg sac. Unlike the smooth, pear-shaped egg sacs of black widows, brown widow egg sacs are spherical and tan, covered with numerous pointed, spiky projections, resembling a sandspur or a sea urchin. These egg sacs are approximately 0.5 inches in diameter and are frequently found attached to the female’s web. Each sac can contain 120 to 150 eggs, and a single female can produce up to 20 egg sacs in her lifetime.
Where Brown Widows Live
Brown widow spiders are found globally in tropical and subtropical climates, originating in Africa. They have spread to numerous regions, including the southern United States, Hawaii, Australia, and Japan, often through human activities like trade and travel. In North America, they were restricted to Florida for decades but began appearing in other Gulf Coast states around 2000, and later in southern California.
These spiders prefer secluded outdoor areas for building their webs. Common habitats include under patio furniture, in sheds, woodpiles, and around building eaves, as well as in garages, storage sheds, and under outdoor equipment like grills. Their webs are irregular and messy, often containing a retreat structure or tunnel where the spider hides during the day. They are also found on man-made structures like barns, fences, guard rails, and bridges.
Understanding a Brown Widow Bite
While brown widow spiders possess potent venom, they inject less venom than black widows, leading to milder symptoms from their bites. Common symptoms include localized pain at the bite site, redness, and swelling. The pain is described as a sharp pinprick sensation initially, followed by a dull ache.
Symptoms can also include muscle cramps, which are less severe than those associated with black widow bites. Nausea, vomiting, and headache are less common but can occur. Only mature female brown widows are capable of biting. They are timid, preferring to retreat or remain still when disturbed. Bites occur defensively, such as when a spider is accidentally pressed against the skin.
For basic first aid, clean the bite area with mild soap and water. Apply a cool compress or cloth-covered ice pack for 15 minutes each hour to reduce pain and swelling. Elevating the affected area can also minimize swelling. Over-the-counter pain relievers can be taken for discomfort, and antihistamines or calamine lotion may help with itching. Seek medical attention immediately if you experience severe pain, stomach cramping, a spreading inflamed area, difficulty breathing or swallowing, or if you are unsure if the bite was from a dangerous spider.
Prevention and Management
Preventing brown widow spider infestations involves reducing clutter and regularly cleaning outdoor spaces. Removing wood or leaf litter piles near homes and barns can help deter these spiders from entering structures. Sealing cracks and crevices in foundations and around windows and doors can also limit their access to indoor areas.
Regularly sweeping away webs and egg sacs using a broom or vacuum is effective. Dispose of removed egg sacs in a sealed bag to prevent hatching. Storing outdoor items like toys, gloves, and gardening tools indoors or in sealed containers eliminates potential hiding spots. Keeping exterior lights off at night may reduce insects attracted to your home, lessening the food source for spiders.
If an infestation is significant, professional pest control services can be considered. Insecticides labeled for spiders can be effective, particularly oil-based products or those with oil-based surfactants, as these may better penetrate the protective webbing of egg masses. Applying these treatments to crevices and holes where spiders hide can help with control.