Insecticides also work against roost mites. Malathion and pyrethrins both work and are relatively non-toxic to the birds and humans. They also break down fairly quickly. Sevin works, but you're not supposed to use it around eggs. As always with chemicals, read the label and follow the directions. (Different insecticides are legal or illegal in different countries, with little rhyme or reason that I can see. Follow local regulations, or at least be furtive.)