Black Widow Influx?

m1chaelNovember 13, 2012


I have noticed over the last couple months the influx of Black Widow spiders in and around our house. My main question is when to know is it time to call an exterminator or should I try some solutions on my own first?

We are constantly seeing them around our garage doors, cement cracks in the driveway apron, outside window wells (basement windows), etc. We moved a portable basketball court a few weeks ago and it was infested with egg sacs and spiders themselves. We clean it all up and moved the BB court to the back of the yard temporarily. We even believe they contributed to killing a plant in one of our mulch gardens by our garage because when we dug around the dead plant to investigate, we saw similar egg sacs to what was under the BB court.

Any suggestions / feedback on next steps or course of action at this point? I was thinking about mixing up a dose of sevin concentrate in my sprayer and just walking around the house and spraying the entire house...not sure if that will help or not.



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rhizo_1 (North AL) zone 7

I know that there is a strong gut reaction to grab for the 'big guns ' when dealing with an over population of a poisonous spider. Sevin is not the chemical to use for a number of reasons.....firstly, as a contact killer, it 'might ' kill those spiders in line for a direct hit but will have zero residual effect. I doubt that Sevin is even recomended for spiders. Sevin will also kill any other critters that may help control these spiders. It's also a dangerous chemical to use around people. There 's no reason to choose that particular chemical.

Having had the pleasure of living through a major BW outbreak myself, I can tell you that the shop vac was our best friend. Put some water with a little dish soap in the canister. Suck the live spiders up, the webs, and the egg sacs. We found hundreds and hundreds of them. Clean up any stacks or piles of stuff around the building and in the garage.

Then, there are several chemicals that are recommended for spiders, most of them in the pyrethrin/pyrethroid family of chemicals. It is those chemicals that the professionals would use though you can find them on your own.

For us, occasional vacuum treatments did the job with that big explosion of the spiders. We kept (and still keep) a broom on the patio just in case...and always inspect the underside of the furniture, the walls, etc. We continue to see occasional BWs in the garage and break out the vac once a year for a good cleaning.

We use Diatomaceous earth in the chemicals allowed around me.

Good luck. Please don't hesitate to call an exterminator if the
Job seems too intimidating. The last thing you should do is apply something that isn't going to work very well...and is so hazardous, to boot.

    Bookmark   November 13, 2012 at 4:40PM
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jean001a(Portland OR 7b)

You need to know that the spiders had nothing to do with the dead plant.

    Bookmark   November 13, 2012 at 10:59PM
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rhizo 1 -

Thanks for all the helpful info...I really appreciate it. So will the "Diatomaceous earth" be effective in helping to control the BW's? And is this something you buy at your local box store like Lowes or HD?

jean001a -

Thanks for clarifying that the spiders did not kill the plant....I guess it was just awfully coincidental that we found egg sacs at the base of the plant after digging around it.

    Bookmark   November 14, 2012 at 8:41AM
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rhizo_1 (North AL) zone 7

Michael, DE can be helpful in controlling spiders and other arthropods that tromp through it. I'd sprinkle it in the nooks and crannies as well as other locations where they tend to hide. Yes, horticultural or food grade DE can be found at any garden center. Don't get the DE sold for pool filters.

I thought that I should stress the 'housekeeping ' aspect of your spider control. As you know, these critters can hide out anywhere. You really have to work at eliminating potential locations.

When we clean the garage, we remove everything. Stacks of firewood have been relocated, empty plant containers are now double bagged in plastic. You get the idea.

    Bookmark   November 14, 2012 at 2:25PM
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