Ok so now that we know how does thrip damage look, let's see the Frankliniella occidentalis, aka Western Flowers Thrips himself.

First, a leaf with initial damage, easy to recognize due to the silverish brights on the leaf surface. If you detect the pest at this very initial stage you are already winning the battle. Spray neem oil or potassium soap and repeat a few days later. Or spray once and next day introduce natural predators Amblyseius swirskii

Second picture is a young thrip. See the green stuff in his guts! Sucker!

Third picture is an adult.

And forth picture, the best F. occidentalis picture you will ever find.

This one is by Dr. Ulitzka R. Manfred @thysanoptera, the wise man behind a website called thrips-id