I buy cheap store brand regular (not anti bacterial) dish soap and use about a tsp in a spray bottle (1 qt). The insects instantly lose their ability to breath. I also used it on an aphid infestation on strelitzia seedlings in the house. Then I just rinse it off after about half an hour.
I also have some neem oil which I am about to try on thrips. Had to get my magnifying glass out to read the microscopic instructions. Haven't actually done that yet though.
I am getting rid of all the thrip magnets in my garden to reduce the temptations. They particularly like Japanese irises but I'm not getting rid of those. So far I am culling out all of the Dutch irises (except Tiger Eye) and all gladiolas. They really seem to go after those plants that have leaves that more or less stay closed around the stalks. My theory, anyway.
