Fowl pox, the dry version. It is a virus spread by mosquitoes, and there is no treatment required, and hopefully, it will only last a couple of weeks without serious effects. It can spread throughout the flock. Do not disturb the scabs and crusts. If scabs are near eyes, Terramycin eye ointment is good to apply in eyes to prevent any secondary infection. If one appears weak and is not eating, look into the beak and throat for any yellow lesions that may be signs of the wet or diphtheritic pox, a more serious infection.