I have a 30 year old pony tail palm with mealy bugs. It is planted in an inside garden with a skylight. Can't move it and it is difficult to reach the top fronds. Plant is about 8 feet tall. Am using insecticidal soap and wiping down fronds I can reach. Spraying the soap and an insecticide where the fronds branch out from the stalk. I heard that mealy bugs go there in particular. 1. Is there a good systemic I can use? 2. Would it be a good idea to pull or cut off heavily infested individual fronds?