Those tiny insects you observed are called thrips. Thrips are very small, yellow, brown or black, slender insects ranging from 1/16 to 1/8 inch in length. Adult and larval thrips feed using a punch and suck technique.

Unlike some kinds of thrips, these on your Ficus are not feeding in buds or flowers but are sucking the juices from leaves. They commonly affect the new growth on Ficus.

Since thrips often feed inside plant structures, using a contact insecticide for control may not be the most effective method. Systemic insecticides such as imidacloprid or acephate, applied as soil drenches or foliar applications, spread to where the insects are feeding and offer more direct control. For the thrips on your Ficus simply pruning off the infested growth and disposing of it is a chemical-free approach. 
 

Additional Resource
http://edis.ifas.ufl.edu/pdffiles/MG/MG32700.pdf

http://ipm.ifas.ufl.edu/pdf/Weep%20fig%20thrips.pub%20(Read-Only).pdf