Question
I just read about how to get rid of scale on one of these sites . It said that once it was removed(I used alcohol and a semihard medium oil painting brush then used a dental tool to remove the ones I found on the base) and they fell into the soil they become immobile and could not reattach so I could reuse the soil.  
It is an indoor plant and I do understand how Birds etc could not get to it to remove them but if they are immobile and in the house how do they move around to get on the plant.
Thanks

Answer
Susu,

For most scale insects the only mobile stage is the "crawler stage" that occurs before the insect reaches an adult. Once they become adult "scales" they can no longer move so if you remove them from the plant they will die. The "crawlers" are very small and resemble spider mites. See http://www.livingwithbugs.com/sca_ins.html for more info. Scale crawlers can be controlled with insecticidal soap (see http://www.livingwithbugs.com/insecticidal_soap.html for details).

Jack DeAngelis