Control cannabis aphids by scouting twice a week, crushing the first colonies by hand, supporting predatory insects, and spraying the undersides of leaves with insecticidal soap or horticultural oil. Start low-risk products during vegetative growth, keep all sprays out of late flower, and quarantine every new clone before it enters the room.
What are cannabis aphids?
Cannabis aphids (Phorodon cannabis) are pale green, yellow, or pinkish sap-sucking insects about 1 to 2 millimeters long. They cluster on stems, new growth, and leaf undersides of hemp and cannabis, and a single unmated female can start a colony without a mate.
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Warm, crowded, lightly shaded canopies suit them. Indoor gardens and greenhouses often see the fastest buildups because wind and rain, which knock aphids down outdoors, are absent.
How do I identify cannabis aphids?
Look for shiny, sticky honeydew on upper leaves, black sooty mold growing on that honeydew, and white cast skins scattered on the medium. Worker ants running up and down the main stem are another strong signal, since ants farm aphids and protect them from predators.
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- Curled, cupped, or distorted new leaves
- Dense clusters at nodes and growing tips
- Winged adults flying to new plants when the colony crowds
- Sooty mold that blocks light and slows growth
Why are cannabis aphids so damaging?
Honeydew and sooty mold reduce photosynthesis, and heavy feeding stunts new growth during the stretch. Aphids also transmit plant viruses, and their bodies and waste end up in flower, which lowers quality at harvest.
How do I control cannabis aphids step by step?
1. Scout and quarantine
Inspect the undersides of leaves and stem nodes twice a week, and check every incoming clone or seedling in a separate room for 7 to 10 days. Catch a colony while it is small and hand removal solves most of the problem.
2. Remove and disrupt
Crush visible aphids with gloved fingers, prune the worst shoots, and bag the waste instead of composting it. Knock aphids off with a firm water spray on sturdy plants, then repeat every few days to break the reproduction cycle.
3. Release beneficial insects
Parasitic wasps such as Aphidius colemani, lacewing larvae, and lady beetles feed on aphids and can hold levels down in closed environments. Release them early, before a heavy infestation, and stop broad-spectrum sprays that kill them along with the pest.
4. Spray with low-risk products
Insecticidal soap, horticultural oil, and azadirachtin-based products work on contact and must coat leaf undersides and stem crevices. Apply in the evening to reduce leaf burn, follow the label rate, and rotate modes of action so resistance does not build.
Beauveria bassiana and Isaria fumosorosea are fungal options that infect aphids under humid conditions. Avoid systemic insecticides during flower, since residues can persist in material that people consume.
5. Manage ants and nitrogen
Band stems with sticky barriers or control ant trails so they cannot guard the colonies. Ease off heavy nitrogen feeds, which push the soft, lush growth aphids prefer.
6. Clean up at harvest
Wash harvested branches in cool water with a mild rinse agent, then rinse and dry them in a well-ventilated space before curing. Washing removes aphids, honeydew, and debris, but it does not rescue a heavy infestation.
Can I use beneficial insects and sprays together?
Yes, if you sequence them. Use soap, oil, or fungal sprays first to drop the population, wait for residues to dry or degrade per the label, then release predators and parasitoids to hold the survivors down.