Electronic flea collars, etc.

I don't know what has happened to the search bar in this forum so forgive me if this is posted elsewhere. Does anyone have any experience with these collars that emit an ultrasonic pulse to repel fleas? I'd like to know how well they work if at all. I'm sick of putting these chemical compounds on my cats. On a related note, has anyone ever used diatomaceous earth to control fleas on their pets and in their environment? Many thanks in advance and if anyone knows of any other "chemical free" alternatives that are safe and that work, don't hesitate to mention them.

The search function is turned off while the site is being upgraded to a larger server. See "Attention All Members" in the Announcements.

Sorry, can't answer your question about the collar, but I'm curious, too. I remember reading somewhere that diatomaceous earth kills fleas, but I can't remember how it's used on cats. I'm not of much use, am I?

Somebody help us out here!!