Hey there Myriam no problemo, I am not familiar with DE but have seen it mentioned numerous times .. I use a dusting powder specific for poultry lice and mites.
I could be way off track but everything so far is leaning me towards mites and/or lice as previously suggested.
Mites will live in the cracks and joins etc, coming out at night to feed on the chickens which would be a good reason for her not wanting to roost.
Does she normally ‘resist’ during the day or at night time as well, if just during the day, I would say that her not resisting now is because it is nightime.
One way to check for mites is to run a tissue over and under the roost during the night .. this will have given the mites chance to have a feed and by doing this you should see blood spots on the tissue where you have squashed them when they are full.
The only other thing I can think of is that she might be getting some ant bites or something similar during the day when she is out and about and like with us sometimes, there is a delayed reaction to the itching process?
How are your other chickens? No signs of similar activity, increased scratching etc.
Another sign of lice or mites can be increased dust bathing in an attempt to rid themselves of them. While they all love a dust bath as a preventative, if it becomes obsessive, that is a good sign of a burden or infestation.
