Entomology (Study of Bugs)/Black Widows


Hi Jessica,

I live in a basement apartment that is invested with Black Widows.  Last summer I killed over one hundred of them . . . mostly in my bedroom!  I can't have poison spray.  Also, when the bug guy came to spray (I wouldn't let him), he said that it doesn't kill them right away . . . they have very small feet.  So I was figuring on half dead punch drunk Black Widows acting in uncharacteristic ways.  Because they were very "reliable" not on any poison.  I always knew where they were or where they might be.  They never were in my clothes or beds . . . always someplace that had an "angle" like a corner or something.  My question is: how reliable are those electronic spider repellents? Not the cheap ones, but the more expensive fancy ones? And since "my" black widows haven't returned this year yet, would it keep them from returning? And lastly, would it make them punch drunk like the poison or would it just make them stay away?

Thanks so much!

Hello Jerri,

I am sorry to hear about your black widow problem, but I do have some advice for you.

First, to answer your question, I don't know that the electronic spider repellents work very well. I have heard some positive reviews, but have not been able to find any solid scientific evidence that they work. If you try them, I wouldn't buy an expensive one. If they work at all, the cheaper ones are likely as effective as the more expensive ones. Also, they tend to have a very limited range, so read the package carefully and place them around your house accordingly.

If I were you, I would use traps instead. There is no poison involved and they are pretty effective. Here is a good one: http://astore.amazon.com/livingwithbug-20/detail/B004I3VKQ8 You should put these near doors, windows and anywhere else they may be coming into the apartment.

Also, make sure you know what juvenile and male black widows look like so you can kill them too. If you are only killing female adults, then you will have a harder time getting the population under control. As you may or may not know, juveniles and males DO NOT look like adult females. Juveniles are not all black and the red marking is usually not as distinct (or not there at all). They can have yellow, white and brown stripes on them (and are often more brown than black). Here is an example, although they can vary some in how they look: http://bugguide.net/node/view/272461  Male black widows are much smaller than females, brown, have stripes and large mouth parts. Here is an example: http://bugguide.net/node/view/13097

I hope this helps. Good luck!


Entomology (Study of Bugs)

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Jessica Mellinger


I can answer questions about invertebrates native to California, including insects commonly found in homes. If you have an identification request, please attach a photo to your question.


I was involved in collection and identification of invertebrates for the United States Geological Survey, Biological Resources Division for six years. Also, I provided these same services intermittently for the UC Davis John Muir Institute of the Environment for many years. I have been a member of AllExperts.com since 2009.

Department of the Interior: United States Geological Survey, Davis Field Station; University of California, Davis Aggie Alumni Association; UC Davis Center for Neuroscience; U.S. Department of Veteran's Affairs

I have two B.A.'s from the University of California, Davis and two Associate's degrees from Sacramento City College.

Awards and Honors
Special Thanks for Achieving Results award from the Department of the Interior

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