By: Hanif Gulmahamad
In early February, a brown widow spider, Latrodectus geometricus (Koch), was discovered by a fourth grade student in Torrance, CA. This spider was found inside a rolled-up leaf of a bird of paradise plant on his school campus.
The find was made during a student field trip with the Natural History Museum of Los Angeles County on the school grounds. The museum outreach educator conducting the field trip teased the spider, its tangled web and an egg sac out of the leaf and placed the materials in a vial. Specialists at the museum later identified it as the brown widow spider.
Museum arachnologists were able to collect 31 specimens of L. geometricus at the school, suggesting a well-established infestation. This is the first record of an established infestation of the brown widow spider in California.
The publicly funded museum contributed greatly to misinformation that followed this discovery. A representative was quoted in one newspaper article as saying: “The bad news is that they are twice as poisonous as black widows.” This statement is not supported by scientific facts, but the media quickly picked it up and ran wild with it: Local headlines screamed “Deadly spider found on Torrance campus” and “Fourth grader finds poisonous spider.”
The week after the discovery, I visited the school and presented basic information about the brown widow spider at a teacher’s meeting. I gave a one-page fact sheet to all attendees. The majority of the questions at this meeting came directly from misinformation people obtained from reading the newspapers.
Although it was a rainy day, I was able to locate two adult females of L. geometricus underneath the dispensing counter of the cafeteria at the school. I also retrieved two egg sacs, and held them in a rearing container in my office. By early March, spiderlings emerged from these egg sacs.
About the same time I had the meeting, a student brought in a spider from his home and told his teacher that his parents wanted to know whether it was a brown widow spider. It was, and the significance of this is that this student lives about four blocks from the school. This find confirmed my suspicion that the distribution of L. geometricus was well beyond the elementary school in question.
On March 27, one of my technicians brought in a brown widow egg sac for identification. It came from near a gutter adjacent to a classroom at a middle school in Carson, CA. On April 3, I visited the middle school and inspected the structure housing the classroom.
Above one of the exterior entry doors of the classroom, near an electrical conduit box, four brown widow spider egg sacs were found in a small web. Inspection of a small, inconspicuous spider web in a metal bracket that anchored a gutter downspout to a metal post of the building walkway revealed five brown widow spider egg sacs and an adult female. Another brown widow egg sac was discovered in a small web on a metal bracket at the bottom of a gate attached to a chain link fence in the parking lot.
IPM strategy
Like the black widow IPM program, the best strategies include physical spider and web removal by vacuum; sanitation and exclusion measures; and a flush with a nonresidual aerosol (and subsequent crushing). Keeping food source pest populations low (cockroaches, earwigs, flies, crickets, etc.) also helps.
However, your most potent and effective weapons are knowledge, education and outreach. Creating an accurate and informative fact sheet on the brown widow spider and handing it out to faculty and parents went a long way in pacifying the situation. Appearing in person at teachers’ meetings and making oral and visual presentations on the brown widow spider, and affording everyone present the opportunity to discuss concerns helped allay apprehension and misinformation. In turn, this helped teachers educate their students on the issue and placate their concerns.
The principals of the two affected schools were requested to refer all future media inquiries regarding brown widow spider discoveries on the campuses to me. By limiting media access to one knowledgeable, authoritative and informed person, I was able to control, limit and prevent further dissemination of misinformation and restrain the sensationalism and alarm generated as a result of prior poor media coverage.
BONUS INFO
Brown widow spider basics
The brown widow spider is believed to be of African origin. It is also reported from Madagascar. It is a typical anthropochore (a spider transported by man from one area to another), and is now found in many parts of the world. It is described as a cosmotropical species that is now found in most tropical seaports around the world. It is well established in Florida, where it is common as far north as Gainesville. In fact, it is the most common Latrodectusspecies encountered in Sarasota County, FL.
This spider varies in color from dirty cream, to light tan, to gray, to brownish, to brownish black. The markings on the dorsum of the abdomen are also quite variable. Because of these variations, L. geometricus is not always easy to identify. The underside of the abdomen bears the characteristic black widow spider hourglass marking. The color of the hourglass ranges from orange to yellowish orange.
The brown widow constructs a characteristic egg sac. It is dirty cream to tan in color and it possesses distinctive stout protuberances on the outside. Its egg sac is much smaller than that of the native western black widow spider,Latrodectus hesperus (Chamberlin and Ivie), with an average diameter of about 7 mm.
They are nonaggressive, secretive and reclusive spiders. The females avoid light, and during the day, they are often found in a retreat in a corner in dimly lit, undisturbed, secluded and protected places. They often extend their webs and venture out farther into their snares in open areas at night. This behavior further limits their contacts with humans. Nocturnal surveillance produces the most accurate counts of a spider population’s density.
When disturbed, Latrodectus spiders often scurry away to their retreat or drop to the ground and “play possum.” I have often seen many western black widow spiders (L. hesperus) residing under picnic tables, park benches, bus stop benches, lunch tables, outdoor patio chairs and tables, and lawn furniture, that were frequently used by people over a protracted period of time, yet no one was ever bitten by these spiders.
The fear and paranoia surrounding these spiders are greatly exaggerated. Many more people die from lightning strikes, bee stings and snakebites than from spider bites. People are accidentally bitten in self-defense when they inadvertently squeeze spiders against their skin, such as might occur when putting on clothing that was stored in the garage or when reaching for materials with bare hands in dimly lit, seldom disturbed areas. The bite of any black or brown widow spider need not be fatal, if promptly treated by a physician. PC
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