Isopropyl and water will leave the least residue, natural insecticidal soap, but try not to spray the buds what ever you spray. beneficial bugs of some sort could be a option too. Introduce thrip predators: Insects such as thrips predatory mites, minute pirate bugs, ladybugs Trichogramma wasp and lacewings love to munch on thrips and can help to reduce thrip populations. Use a natural insecticidal soap: These work best for moderate infestations.
I run a small grow so keep that in mind. I was using Dr Bronners soap to spray the leaves but it leaves a taste to the buds even when I wash them.
I am using transparent tape on the end of a pencil or on your finger. I touch the tape to the thrip and away he goes. It takes some time but controls them. I can see them mostly but sometimes use a magnifying glass to help. They hide on the bottom sides of the leaves at times. Run the tape around the end of the pencil and after a full turn, reverse direction and the tape will stick to itself while leaving the sticky side facing out.
I forgot to add, the thrips when young are white and later turn black with a bit of white. Same bug different stage of life and color. The white ones are harder to see. They reproduce in the soil so a drench of soap and water could do the trick. I am just using the tape right now and it keeps them in check.
Thrips are elongated insects that live down in the leaves and flower, they don’t look like fungus Gnat. They don’t cause much trouble in cannabis but can be annoying. Swiriskii mites will eat them or Orius bettles.