I have not had many problems with Huperzia except this white scale. This pest takes it home under the tips of the Huperzia and eventually will kill the plant. White scale does not grow as fast of brown scale but it is not as easy to kill. I use Eight (permethrin) by soaking the ferns in bucket solution every 8 days for 2-3 treatments. If you are able to look threw a lens you can tell if the problem is taken care of or not. The white spots do not go away that is the housing for the scale insect. But in a month you will see new growth. Not dealing with this pest will lead to wide spread infestation.