wall carpets

I am looking at the First Defense product to help us deal with a flea problem.  Our house is mostly hardwood floors, but we also have wall-to-wall carpets and rugs, including oriental rugs.  I’d like to know whether the product can cause any damage to carpets or rugs, and whether it will leave any visible trace or residue on any of them, including ones with dark colors.  Also, can you tell me whether the product lasts as long on woven rugs, which are not as thick and don’t have the same texture.

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