DE= Diatomaceous Earth
Okay, here is the deal. Frontline, spray or topical application (between the shoulders) is rarely affective any longer. The best methods for getting rid of fleas these days is using Eucalyptus oil, diluted, and rub into the fur onto the skin. Especially areas of high flea traffic, under the neck, throat, back of the head, under legs, and on abdomen. Flea dips still work, but there is alot of danger associated with them. Use only as directed. If directions specifically say for dogs, only use on dogs as these chemicals formulated in dog dips can cause serious health problems and death in cats. If the products specifically says for use in cats, likewise, only use on cats. I recomend dips (and I hate chemicals) when the situation is bad. I cannot stand a flea. But only use when neccesary, and ONLY as DIRECTED!
For use in getting rid of them in the house, you can use D.E. but a more effective method is to use 20 Mule Team Borax, or any powdered laundry detergent, GAIN smells so good, sprinkle through the house, onto the carpet, hardwood (watchout slippery) and furniture. Wait 20-30 minutes and then vaccum. You can leave on carpet longer, as in for a few days, but it may leave a greasy residue that won't appeal to your feet too much. You can do this once a week or twice a month (depending on carpet, size of house etc.) and I garauntee you your flea problem will be gone. You can also use Borax on the animals coat, or dip them in a mild solution, fill the bathtub and do 1/4 scoop(cats & small dogs) 1/2scoop(medium dogs dogs) 1 whole scoop (large dogs) and wash them in this. May irritate their skin slightly, but it's more from the irritant of the fle bites, a dip will cause the same effect but through use of caustic chemicals. Dish detergent as mentioned above can be used as well, fleas can't stand it, and you can safely mix dish soap with the borax mixture to use as a bath.
Last but not least.....vinegar. The animal may smell strong, and the vinegar will at first burn in any flea bites but will actually help heal and soothe the skin in the long run. The acidic nature of vinegar will kill the fleas. You can use white distilled or apple cider(better smelling) and they will equally be effective. Good luck!