Of
course you don't have to use DE
Some people do, some people don't, no biggie.
As far as its action in helping control lice/mites, especially when dusted into the feathers of infested birds and in parts of the coop where they might also be hiding, your main alternative choice is Sevin (a mild chemical pesticide, probably IMO not quite as safe as food grade DE but not horribly massively toxic)(don't breathe *either* of 'em into your lungs, of course)
As far as absorbing moisture in the coop, alternatives include solving the moisture problems by management or repair, or using stall dri or sweet pdz (or any other comparable brands). I would not put lime where chickens will be walking/breathing directly in it, but some people use it in small amounts with no apparent problems.
As far as using DE as a worm preventive (which IMO the jury is still totally out on, in terms of well-produced numerical evidence, personal anecdote aside) there are other quote natural unquote things that some people feel will help prevent worms or cure existing worms, such as pumpkin seeds and/or buttermilk (see my comment above re: well-controlled empirical evidence for this doing any good); or you can just wait until/unless an actual worm problem develops -- likelier sooner in a free range flock than in a confined one -- and then treat with a chemical wormer that is known to handle the particular worms you have. While some people worm preemptively on a schedule irrespective of fecal tests, the fact that chemical wormers have not been well-tested to characterize safe withdrawal period for eggs, and can cause abnormalities in hatching eggs, and can be a bit hard on a bird's system, and you don't wanna be breeding up resistant worms, would suggest *to me* anyhow that it is probably better to leave things alone til a problem develops. (Others opinoins may of course differ)
Anyhow, DE probably does have useful uses, but none are essential and unsubstitutable
Pat
