apply the dust the day after u water, if u water while the dust is on the soil it will cake up or wash away rendering it useless spread enough on that there is a thin layer across the whole top of the soil. Get some hanging sticky traps, make sure they are the baited kind, they work wonders. let ur coco dry out a lot between waterings as eggs can only be planted in wet soil, a week of dry soil will decimate there numbers