Beware of Brown Widow Spiders

Beware of Brown Widow Spiders

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Brown Window Spider I knocked off the trash can and on to the driveway

Generally, I really like insects, and very few bugs make me squeamish, but this one really freaks me out: the Brown Widow (latrodectus geometricus.)  I was showing someone an egg sack to look out for today, and figured I could post about the spider since they are now a regular occurrence in the garden. I didn’t enjoy taking the photos at all.

Brown Widow spiders have moved into Southern California from Florida, where it was introduced from the tropics.    In recent years, reports of this spider have been widespread throughout Florida, coastal areas of Alabama, Mississippi, Louisiana, Georgia, Texas, South Carolina, and Southern California. We have been finding them in Long Beach since about 2007.   I did some research after a neighbor brought me one in a jar that year, and I originally thought it was just a juvenile black widow spider.  Around that time was when we also started to notice the new unusual egg sacks, too.

Around our neighborhood, they are found on the undersides of the trash can lip where we would normally grab to move the can, children’s plastic play equipment, wagons, patio furniture, around the bbq, plus any other places that the black widow likes, like corners or crevices.  They make messy cobwebs.  I have seen the chickens eat these spiders! Unfortunately, most of the brown widow spiders are in places the chickens have a hard time reaching into.  Instead I keep an old pool cue handy near the trash cans, and I try to regularly tip things over and squish the brown widows and their egg sacks.  I usually don’t like to kill spiders because they are beneficial, but these guys seem less shy than black widows when disturbed.  Brown Widows are more poisonous than black widows from what I have learned, but they inject less poison in their bite.  I find it necessary to kill these when I find them.

Brown widow spiders can range in color from light tan, dark brown, or almost black.  They may have different markings such as white, black

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Brown Widow Egg Sack under the trash can lip , yellow, brown and even orange on the back of their abdomen.  The ones I find around here, the legs are often striped  or banded.  The hourglass or other marking on the underside of the abdomen can vary from yellow, orange, or red.  They have the shiny “plasticy” look that black widows have and the same shape.  However, the egg sacks are very different.  They look like liquid amber seed pods, spiky and prickly in beige.  They often have more than one egg sack.

Sorry, I don’t have any great pictures of the abdomen markings. As soon as they move around, I freak out and squish them rather than try to turn them over for a better shot.  For good photos of the underside, do a google search or go to my favorite bug site:  What’s that Bug for a brown widow belly picture.  Here is another excellent source for more info on Brown Widows and other invasive insects: UCR Center for Invasive Species Research

4 thoughts on “Beware of Brown Widow Spiders

  1. Hi there! A fellow Long Beacher here, and when we first moved into our house 4 years ago, the backyard and garage was filled to the brim with these spiders! *shudder* After a couple seasons of finding and destroying egg sacs, we still see a couple here and there, but not enough to be too scared of going outside. We also have chickens, and I was shocked and scared when they ate their first brown widow, but they seem to be completely unaffected by the venom. So strange!

    1. Thank you. There are not many things I dislike about Southern California’s climate, but this is one of them. Just like people, this spider decided it was a great place to live.

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