Use traps, this type of insect is attracted to the color yellow; yellow strips of plastic covered in glue on both sides which, when placed strategically among your plants, will cause the winged adults to stick to it. Place them at a prudent distance from the plant, otherwise, a gust of wind or a fan could cause the leaves of your cannabis plant to stick to it. You can also spray it with biological insecticides: spraying Neem oil, pellitory, insecticidal soap, and Wormwood or Tansy infusions effectively eliminate whitefly. Apply them insistently at intervals of 5 or 6 days until the infestation disappears.