I use it undiluted. A little goes a long way. When I say spots with the brush, that is literal. Use tea tree or lavender with it for wood that will make it easier (as neem solidifies when cold). I spray nests with neem lavender and tea tree. Good prevention, plus they (mites) just bail out if...
I use neem oil. I just use a little paint brush to do legs then spots under wings, vent and tail gland. Works fast. The hormone like substance in it confuses blood sucking pests, to the point where they can't eat or reproduce. Disturbing their breeding cycle. I do perches too like you. Then I...