If you see bugs on your pants from a hen, they were likely Northern Fowl Mites or lice.
Northern Fowl Mites look like black specks of pepper scurrying. They drop off fairly easily.
Lice are straw colored, which would be harder to see on pants (unless you were wearing dark jeans). Lice tend to stick better on the bird as well.
Both NFM and lice live on the bird and are active during the day. (There is also Red Roost Mites, but they live in the coop and feed on the bird only at night. They are red looking pepper scurrying very quickly...or globs of black and red "fish eggs" in the corners and crevices of your coop).
To be certain, go out with a flashlight and check at the vent. If you see black scurrying pepper...NFM. If you see straw colored slower moving flat bugs, with clumps of white rice on the base of feathers, the nits, lice.
Either way my treatment of choice is not DE (which does not work very well in my opinion) but permethrin poultry dust. Simply dust with your hand or filled sock at the vent and under the wings. Putting the dust in an old nylon sock helps direct it better. Use it like a powder puff. Retreat in 7 to 10 days to break the cycle of juveniles/adults.
You should treat the whole flock as lice/mites wander easily.
Also clean out your bedding. While lice/mites live on the bird, they can transfer from dander on the bedding for a few hours.
Quick thorough steps now will put this in check.
LofMc