Black dots on stems

Today on a closer look at my Hibiscus plant. I saw that I had a lot of black dots (about 1/8 inch) on a few of the branches. I tried taking them off with my fingers & they would crush while I was trying to remove them. Does anyone know what they are ? How do I prevent from comming back. Am I in real trouble with this plant ? I do not want to lose this tropical hibiscus plant I have had it for over 5 years & it is very large. It was over 6 foot tall before I trimed it down last weekend. Please I do need some serious help. Jake

Are the black dots three dimensional? If so it sounds like scale. Here's some info: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7408.html