Weird pattern of feather loss/breaking off! PICS

[1Teacherchick]

Not an emergency, but Henrietta, my barred rock hen, has bare patches on her chest and on the arch (top) of her wings, where the feathers are broken off or missing. We sprayed SEVIN in the coop, changed all the shavings in the bottom, put Frontline on all the hens, and sprinkled their dust bath area with SEVIN powder. 3 weeks later, it is worse than before. She is not being picked on by the other hens, and she is healthy and laying well. They free range for 10-12 hours per day. Any hints, suggestions, or answers?
Thanks!

 

[ChickenGrit]

Do you have a rooster?

 

[Eggcessive]

Does she have feather mites? Apparently sevin dust and permethrin work well, but they have to be repeated every 4-7 days for feather mites. I haven't had this before but I have read that once the feathers are damaged, it might take until after a molt for the feathers to grow back in well.

 

[dawg53]

I recommend giving her spinach to eat. Here's a link for you to read:
http://msucares.com/poultry/feeds/poultry_feathering.html

 

[1Teacherchick]

ChickenGrit - We don't have a rooster. Eggcessive - We didn't repeat the pesticide treatment, so I will try to do three rounds of pesticide about a week apart. She is about a year old, so I guess we'll have to wait until her molt to see if they grow back. dawg53 - I never thought that she might be eating them herself. I'll have to watch that. In the meantime, I'll look into supplementing with spinach. Thanks everyone!