Will do!
I know, poor girl. I feel so bad. I will check her again for bugs.
Yes, I treated all my chickens for bugs (btw: what's the difference between mites and lice? how do I know which I'm dealing with?). I couldn't find the product you recommended, so I just bought some food-grade diatomaceous earth, and dusted them all with that.
My parents know nothing about chickens, so I'm kind of on my own here, unfortunately.
Mites have 8 legs and often live in the coop/housing coming out to feed at night. They feed on blood, so can cause anemia and weaken the bird. Make them sick.
At night, you can run a paper towel along roosting bars, see if it come clean or you have bugs or little bloody spots on the towel. This will help you know if you need to treat your coop asap.
Lice have 6 legs and for the most part live on the bird. They are a little bit larger than Mites and you can usually find them if you look through the feathers, especially around the vent, under the wings and on Silkies, top of the head (for some reason).
DE may help a little, but when you can, try to get a Permethrin based poultry dust to dust all the birds. This time of year,
TSC should have it, you may have to look in the horse section, where the Fly/Pest spray is.
The concentrate will last a long time and make many gallons of spray. Since it's cold/winter, you would not want to spray the birds, so dusting is usually best for winter.
I'd mix up the concentrate, then spray the coop on a day that is sort of sunny. Focus on roosting areas getting the spray in the joints/nooks crannies and in the nesting boxes.
The powder, put the powder in an old sock, the shaker can is terrible. Use the sock like a powder puff and "powder/dust" the birds, getting under the vent, wings, etc. Work the dust all the way down through the feathers to the skin. Store the sock in a jar with a lid, that's what I do. Be sure to label your jar so you know what it is. The powder will last a long time if kept dry and in a jar.