The most common mites and lice are Red Mite, Scaly Leg Mite and Northern Mite. They live all year round and multiply quickly. Most mites and lice are nocturnal and like to live in the dark parts of your coops, typically these are the hardest places to reach. The best way to combat this is to either use a liquid spray or a powder.
If they are living on your bird you can dust bath your bird in the powder. Check for mites by looking in the coop (usually under the perches), check around the neck and the vent or check your bird. If your bird has mites or lice then egg production and weight will decrease.