I'm trying a new type of Diatomaceous Earth. The new stuff is food-grade and can be taken internally. Fleas have been very bad this year, and I can't keep up with them. I have the DE around the outside of the house, but the wonderful product I have has some added ingredients that make it not quite food-grade. There are no pesticides in it, but if the cats or myself eat it, we may not like it.
So, I've purchased a food-grade version of DE, and I'm going to put some on the cats in their flea-infested hotspots, and then rake a little into the carpet. That should finish with any fleas we have in the house.
What I've been finding is that the fleas are not getting in, but they are breeding on the cats. Fleas have a lifecycle that is purely based on their feeding cycle...
They feed and lay eggs. The eggs hatch into larvae about 10-20 days. They mature into adult, biting fleas in 20-30 days, and the cycle begins again. If you can stunt their growth in the larval stage (Frontline, Ovitrol) then they never mature to lay more eggs and die off. If you have adult fleas, you need to kill them (Advantage, Siphotrol, pyrethrins) and then treat again in 30 days - but they may already be laying eggs, so I recommend a third treatment to fully rid yourself of fleas.
And all the places where fleas can hide must be treated: rugs, furniture, pets, bedding (including yours), and the landscaping around the entrances to your home. That's what makes DE so convenient! It can be left out year-round, and not hurt the beneficials. It also kills other pests (such as beetles, silverfish and earwigs) and parasites (such as the worms caused by fleas - when ingested).
I'm also curious regarding DE's general health effects for humans. It clears out the parasites and muck in the digestive tract, and can be good for overall health. So, I'll report back after I've received it and tried it for about a week or so.