I had insects that look like that all over my stevia plant. I also had a bunch of other stuff. My solution was to:
Crush 2 cloves of garlic in a medium glass of water and leave it for 2-3 days
pour that mix into a spray bottle with a dab of dish soap (I use organic env. friendly(er) stuff) and a touch of olive oil, about 1/2 tsp.
Then I sprayed the TAR out of the plant, inside out top to bottom when the sun was setting.
All the bugs are off my plants, I had quite the mixture of bugs and they all went away after the second application.
There where absolutely no repercussions from the plant. Healthy as ever.
You may wish to cover you soil to prevent it from over dripping into it, I didnt do this however.