Not sure what the weather is like in Illinois but I would not spray a bird in winter in my climate, especially at night when they are not active.
In a colder climate I find that lice which is what these sound like, are more likely to thrive than mites which live in the cracks and crevices of the coop. Lice are more of an irritant than a serious health threat because unlike mites which suck blood, lice live mostly off skin debris.
In a colder climate I find that lice which is what these sound like, are more likely to thrive than mites which live in the cracks and crevices of the coop. Lice are more of an irritant than a serious health threat because unlike mites which suck blood, lice live mostly off skin debris.