unknown bugs on grapefruit tree

sensorineural starts with ...
Hi

I have a mature grapefruit tree in my garden that I transplanted successfully about two years ago. It is still on the road to recovery and hopefully will fruit this season.

However, I have noticed that there are quite a few of these bugs on the tree. they don't seem to be interested in lemon, orange, or cumquat tree.

They don't seem to be eating the leaves but they just walk around the leaves. Its antennas are constantly vibrating and they are really REALLY quick. If you touch the leaf they are on they scurry away very fast.

I can't seem to find out on google what they are and what I should be doing about it.

can anyone be of assistance?

Pictures - Click to enlarge
Picture: 1	Picture: 2