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FROM THE ARCHIVES: Brown Widow Spider

By Walter Andersen, first published in Let's Talk Plants! November 2009, No. 182.

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The ventral (under) side of a brown widow spider, Latrodectus geometricus with the orange hourglass marking clearly visible. Captured and photographed in Los Angeles, California. The image is a 12 frame focus stack. Matthew Field,

[2009 Editor’s note: As we go to press I got a series of e-mails from Walter Andersen, relating his experiences in mid-October 2009 with a Brown Widow spider. Take care in your garden to avoid getting bitten!]

I was working in Poway and a lady came in with a bag and took out a clump of leaves off of her citrus tree. She brought it in to confirm what she thought it was. She said, "I think these are Brown Widow Spider eggs."

I had heard of them being in our area recently, but have never seen one, nor the egg sac that I know of.

Anyway, another lady was in the store and came to see what was there and she said, “Yes, definitely those are Brown Widow Spider egg sacs.”

She had an I.D. card hanging from her neck, I put on my reading glasses and it said “Ann Sixtus, Department of Agriculture.”

I asked, “do you work for the Ag Department?”

She said, “yes, I came in to check the orchids you received from Hawaii.”

It was pure coincidence that they came in at about the same time. But also, it was great to have an expert confirm what the first lady suspected.

I put the small branch in a plastic bag to take home to take a photo, and also to have "show and tell" in San Diego. Jody and I were moving the leaves to get a better shot and Jody says, “There she is!!!!”

Sure enough, the spider was hiding in the leaves. Jody rushed to get a jar and we stuffed it all in the jar for tomorrow, sealed with clear packing tape too.

I thought you might want to put something in the newsletter that Brown Widows may be hiding in some of our shrubbery and to be careful, especially where the foliage is kind of thick.

With this branch, we had to carefully peel away some of the leaves to get a good look. I have another photo my daughter-in-law took at the store; it shows more of the webbing.

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Brown Widow with her egg sac.

Ann Sixtus, the Ag lady, said they have a distinctive egg sac: they look like they have thorns, almost like little white Liquidambar seed cases. The egg case is about 7/16” in diameter and almost white.

There was fine webbing almost covering the space they were in. There were five egg sacs in the group.

This spider has more of an orange color to the hourglass shaped spot than the Black Widow.

If you Google it you can see at the joints of the legs those areas are much darker than the rest of the leg. I think it is pretty easy to identify by the spot on the belly, the light and dark legs and the spiney egg sac.

Anyway, I thought it was interesting. Ann Sixtus said when she is working in her yard she always wears gloves, just in case, to protect her hands.

Often when I pick up a 15-gallon size container with a lip, in the back of my mind, I think, “is there a Black Widow under this lip?”

I do see Black Widows often but have never been bitten. I don’t know of anyone who has, but they are out there. Some information I read about the Brown Widow says they are more toxic than Black Widows; other sources say it is not as bad. Anyway, they are around, both of them!


The 2009 Let's Talk Plants! newsletter editor (and president) was Susi Torre-Bueno who also happens to be the SDHS 2012 Horticulturist of the Year and Walter Andersen is our 2002 Horticulturist of the Year.


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