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Roger L. Welton, DVM
Roger L. Welton, DVM, Veterinarian
Category: Cat
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Experience:  Licensed Veterinarian, Practice Owner, and Book Author
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We have indoor/outdoor cats. We also have an infestation of

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We have indoor/outdoor cats. We also have an infestation of black widow spiders in our yard. Is there a product which will kill the spiders but whose residue will not harm the cats?

Hello,

 

Black widow spiders certainly pose a dangerous risk to your cats and your human family. It would most definitely be in your and your kitties' best interest to eradicate them.

 

Diatomaeous earth is an organic powder commonly used in pool filters because of its fine texture and subsequent ability to filter the pool water. You can get it at Lowes in the pool section.

 

To treat your yard, simply sprinkle a generous amount around the yard. Pay particular attention to the areas immediately around your foundation, as these are common areas spiders will loiter around, looking for a way into homes...you do not want these creatures in your home!

 

Diatomaceous earth is 100% safe for mammals, however, not so for insects. It works by penetrating their exoskeleton and then dehydrating them by sapping their internal body fluids. Again, this does not occur with people and non-insect animals, so you should have no fear for wildlife, human occupants of the home, or cats, dogs, etc.

 

In addition to this, since spiders like to set up shop on vertical areas, such as trees, fences, corners of the outside of the home, you may wish to spot kill spiders that are on vertical surfaces if you can reasonably reach them. You can use Raid spider killer for this, as you would only be spot treating in focal areas, not doing a blanket treatment of the whole yard.

Customer: replied 3 years ago.

Hi Dr. Welton,


 


I'd like a little more detail:


 


1) How long does diatomaceous earth take to kill black widows?


 


2) Is any contact effective or does the powder have to be on the main body (as opposed to just walking across a powdered area?


 


3) Are repeated applications necessary for the first kill?


 


4) How often do you recommend future applications to prevent future infestations?


 


5) If the powdered area gets wet and then dries out, is the powder still effective?


 


6) I have heard from multiple sources that none of the consumer level products is effective for black widows. Will Raid spider killer really do the job?


 


7) Does Raid spider killer pose any risk to people or pets?


 


Could you could number your answers and/or intersperse them with the questions?


 


Thanks.


 


 


 


 


 


 

Excellent follow up questions. I will address each one itemized:

 

1) How long does diatomaceous earth take to kill black widows?

 

I am not exactly sure, as I am not a pest control expert. Feedback I have gotten is singificantly reduced spider, ticks, and other insects within one week.

2) Is any contact effective or does the powder have to be on the main body (as opposed to just walking across a powdered area?

 

They just need to walk across it, as it penetrats their exoskeleton on contact.

 

3) Are repeated applications necessary for the first kill?

 

Weekly unless there is a big rain or string of consecutive days with rain, then i would reapply sooner.

 

4) How often do you recommend future applications to prevent future infestations?

 

As a preventive measure, you can apply biweekly throughout the spring and summer months, bump it up to weekly if you find that pest control is wanting.

 

5) If the powdered area gets wet and then dries out, is the powder still effective?

 

It is definitely still effective, but after a good rain, it may drain off or absorb into the soil to a point that the concentration is not high enough to be effective. As such, it would be wise to re-apply after a day of torrential rains, or after 2-3 days of mild to moderate rain. You can physically see it in the grass and soil, as it is a different color than regular dirt..spot inspection after rain can help to let you know if it is time to reapply.

6) I have heard from multiple sources that none of the consumer level products is effective for black widows. Will Raid spider killer really do the job?

 

Raid Spider Killer should kill any spider, but again, I'm not a pest control expert.

 

7) Does Raid spider killer pose any risk to people or pets?

 

It is probably not ideal to have prolonged contact with this product human or pet, which is why I would only use it for spot treatment on the aforementioned vertical areas and corners, rely on the organic diatomaceous earth for the more broad treatment.

 

Hope this helps. Please let me know if you need further clarification on any points. Best regards,

 

Roger Roger


 

Customer: replied 3 years ago.

My partner is a respiratory therapist and she says it would be harmful in breathe in diatomaceous earth particles, so we probably won't use it unless we can find suitable—and affordable—protection.

It is in most pool filters. Does she also disagree with using it there? The diatomaceous has to be changed every 2-4 weeks. If it caused harm to people, one would think that a nation of pool owners would - me included - would be showing epidemic respiratory disease.
Roger L. Welton, DVM and other Cat Specialists are ready to help you
Hi Fred,

I'm just following up on our conversation about Zeke And Maurice. How is everything going?

Roger L. Welton, DVM

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