Guard n Aid Thrip is a Pyrethrum based insecticide which is effective as a control against all stages of the Thrips life cycle. It is about as effective as any spray against these most voracious of enemies to the indoor grower without a licensed chemical - or the kind of thorough eradication techniques that can be employed between crops. As such do not expect a one-hit solution to the problem, the spray should be reapplied every 7 to 10 days for as long as possible into the fruiting cycle without risking damage to your crop by over-spraying later on in their cycle.