I wouldn't, just to be on the safe side.
FYI?
Food Grade DE, in all mammals I'm aware of, can be an effective prophylactic ... i.e. reduce rate of infestation and help maintain gastrointestinal health IN MODERATION when mixed daily, fresh, with NON WET feed in a non wet environment; I'm new to chickens... but in others? Once they have a case? Not an effective treatment... medication is recommended. In other animals, infestations can pass from critter to critter, so DE can only do so much.
The individual who mentioned the 'wet' part is correct, but the mechanism of action is a bit more complicated.
Wet DE is still fossilized diatomes. In that sense? Yes: it will act on mites and no seeums in the same capacity. Many believe this to be desiccating action, and that may be partially responsible, but the actual cause of death of these mites, etc, occurs due to the diatomes acting as sharp blades within the mites, etc.: they're essentially cut up from the inside out. This is why it effective only on small mites and eggs, etc; and why it is not dangerous to large critters: i.e.: we are larger; for us: it will not cut us up, but act more like an insoluble fiber or dietary clay.
However, the type of DE I've been told to get for my chicken, the red earth type? Is particularly prone to 'muddying'. Of course any will... but this, I found after a rain, is thicker... sort of... The consistency, by nature, is different: the red earth type has elements not in food grade 'white' DE, these are more 'clay' or 'cement' like when wet.
As I understand it, the problem isn't precisely that wetness renders it ineffective, because water doesn't alter the atomic structure of the diatomes... BUT, this 'mud', if fed to a chicken, can not be 'digested' nor pass unimpeded through the GI tract and can, indeed, cause impacted crop or bowel {or digestive organs, I believe, in chickens, too} blockage. And in this sense? Muddy Red Earth DE is both dangerous and potentially lethal to chickens, unlike it would be, say, for a cow, in similar quantities. It is this mechanism, then, that renders the Red Earth DE ineffective: Dead is dead, thus the no-see-um killing action is therefore a moot point.
This is my understanding; again; brand new to chickens.
Caveat: I am not a vet nor am I a health care practitioner.
Good luck!
I thought perhaps a deeper understanding of the action at the molecular level might help you wrap your head around it; that always helps me!
Take care.
