Pyrethrum is what I usually use. I have a huge bag of Sevin and I thought was the same thing. I just used it for the first time for a lice infestation and it worked great.Pyrethrum (not permethrin or sevin) is made from chrysanthemums. Here are some good links to read with pictures of lice and mites for identification:
http://www.the-chicken-chick.com/2012/08/poultry-lice-and-mites-identification.html
http://anrcatalog.ucdavis.edu/pdf/8162.pdf
http://ohioline.osu.edu/vme-fact/0018.html
Usually I sprinkle Pyrethrum in the favorite hen dusting spots and the coop but have lately slacked off which is how we got the lice in the first place. Lesson learned.
Gross right? I want to suggest that anyone undertaking a lice/mite clean up take some Motrin before starting.I just did this Fri.....same thing...a bizillion of them.....after your done you feel like you need to take a bath in Gas!
still feel itchy 3 days later!