Texas Brown Widow Study

Texas brown widow spider distribution study

Brown Widow Spider
eggsac (c) CISR

UC Riverside is conducting a collaborative study with Texas arachnologists to determine where the brown widow spider lives in Texas. This spider is an African native, became established in Florida in the 1930s and spread like wildfire from Texas to South Carolina in the first decade of the 21st century. It has taken over urban and suburban areas where it establishes. We are asking citizen scientists to help us in documenting the presence of the brown widow in Texas.

Before going any further, the brown widow is not a very toxic spider so DO NOT worry about your children, grandchildren and pets. Bites are very rare and mild when they occur. (See a more extensive note below about toxicity.) If you have any concerns of being bitten by a spider, DO NOT bother trying to interact with it. But if you can take photos without getting too close, that might work. Better yet, just as useful are photos of the egg sacs which of course are harmless.

Distribution study
For the study, we need evidence (either pictures or the actual specimens) and the location where the spider or egg sacs were found. Please include the CITY, COUNTY and if possible the ADDRESS or GPS coordinates. The reason for the address is that we may attempt to do a GIS study (Geographic Information System) where we correlate the distribution with environmental factors. If you do not wish to give your actual address, just give an approximate one (like, hey, one of your nearby neighbors’ addresses or a nearby business; that will be close enough for our calculations).

There is great variation in coloration of brown widows from almost white to almost black. If you wish to see more on how to identify a brown widow spider go to the CISR website page on Brown Widow Spiders.


There are several ways to send us the data:

1) The best way is to take pictures of the spider or, of greater use, its spiked egg sac and email them to the address below. However…………..
  • No “Bigfoot” or “UFO” caliber photos in bad focus. These are useless.
  • If you take pictures of the spider, we need to clearly see the topside of the abdomen (see photo above). DO NOT take pictures of the underside with the hourglass because other native Texas widow species have similar looking bellies. You might want to first kill the spider by freezing it or spraying with insecticide and then safely take pictures after it is dead.
  • If you can crop the photo and get rid of the uninformative background, please do. Sending a picture that is 98% background is not going to help us identify the spider and also makes the file much larger than it needs to be, clogging up the email.
2) Sending evidence by mail
  • First off, it is a violation of postal regulations to send live spiders. DO NOT send them alive. Therefore, if you wish to send material, please freeze the specimens (either spider or egg sacs) and then mail them
  • If you send egg sacs, just plop them into a small container (such as an amber-colored prescription pill vial or small food storage container) or padded envelope and mail them to the address below
  • If you send dead spiders, please put them in a small container like a pill vial with a little paper toweling inside to sop up body fluids if they leak and tape the lid to the vial. Please mail in a sturdy box or padded envelope. In the past, some vials were thrown into flimsy envelopes, were shredded in the mail handling process and the container was lost.
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Subject: Texas brown widow study

Rick Vetter
Texas brown widow study
Univ. Calif. Riverside
Riverside, CA 92521


Toxicity (longer version)
The bite of a brown widow is mild. In a study of 15 verified brown widow bites in Africa, the two most common symptoms were that 1) it hurt when it happened and 2) there was burning pain at the bite site. This is nothing compared to the dynamic events following a black widow bite. Some people have had more severe reaction to a brown widow bite but to put it in perspective, in Florida, the spider has been around for almost 80 years and Florida’s arachnologist says that he is aware of maybe 4 bites in all that time. In southern California, the brown widow has taken over urban homes throughout Los Angeles and San Diego, there are probably billions of brown widows now living among the 5 million people out here and in 10 years, only one bite is known to southern California arachnologists. For those of you who are concerned for your children and pets, they are more at risk riding in a car than being harmed by a brown widow.

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