Had a problem with thrips too a short while ago, used Pyrethrum 5EC from pro grow and a bonus of being 100%certified organic. copied the next bit from the website but thats what sold it for me.
Kills thrips, spring tail, whitefly, aphids, flea beetle and caterpillars.
*this is THE most effective organic spray for the control of thrip. Anyone who has suffered with thrips will tell you what a pain they are to get rid of. At last we have found a 100% organic spray that finishes them off good and proper!
• For use on all plants, vegetables, soft fruit and ornamentals.
• Great for use in indoor or outdoor growing systems.
• Leaves no residues.
• Harvest just 24hrs from last treatment.
• Also controls Spring Tails.
• Can be used in certified organic systems.
Dilution rate: 4ml per 1ltr of water as a spray or 2ml per 5ltrs in solution for the control of springtails.
Chesney.