Whiteflies are tiny, white, sap-sucking insects that hide on the undersides of cannabis leaves, and they can do serious damage before you even notice them. They spread plant diseases as they feed and hop from plant to plant, leave sticky honeydew behind and can travel long distances. Whiteflies feed on the leaves and stems of weed plants, which makes them one of the most destructive pests a grower can face.

How do you spot whiteflies on cannabis?

Checking for whiteflies is easy: just give the plant a shake. If a swarm or cloud of what looks like white dust or tiny white moths flies up around it, your plant has whiteflies.

One of the main signs a plant is dealing with whiteflies is chlorosis, which basically means the leaves turn yellow. The leaves dry out around the edges and eventually drop. Growth slows down and the plant goes downhill.

How to get rid of whiteflies (and keep them out)

Whiteflies have built up resistance to a lot of pesticides, which makes them a nasty enemy. The smart way to control them is prevention.

Keeping your indoor grow clean is essential. Dialing in humidity and temperature and keeping the room clean and well ventilated all help keep them away. Inspection is key: always check the undersides of the leaves, where they hide, and shake your plants every time you tend to them so you catch the pests early.

Outdoors, companion planting is a great natural way to stop a whitefly invasion. Planting zinnias between your cannabis plants, along with calendula (pot marigold), helps push them out of the garden or grow area.

Zinnias attract the whitefly's natural predators, like hummingbirds, predatory wasps and flies that hunt whiteflies. Hummingbird bush and bee balm are a couple of examples of minty-smelling plants that mask the scent of nearby plants that draw whiteflies in. Mint works well too!

How do whiteflies damage weed plants?

Whiteflies can do real harm to a cannabis plant's development. They feed on the sap in the leaves, which weakens the plant and can damage its structure. Common symptoms of a whitefly infestation on weed plants include leaf discoloration, yellow or silvery spots and an overall weak plant. On top of that, whiteflies secrete a sticky substance called honeydew, which can encourage mold and other pathogens.

If you don't get them under control, whiteflies can spread fast and hit both the health and the yield of your cannabis plants.

Why do whiteflies show up?

Whiteflies tend to show up when conditions suit them, especially in warm, humid environments. That kind of setting is perfect for them to breed and multiply. Plants that are already weakened, whether by nutrient shortages, stress or disease, are also more likely to get infested.

If you're dealing with a whitefly infestation, it's important to act. There are several ways to control and eliminate them: whitefly-specific insecticides, yellow sticky traps to catch the adults, beneficial insects like parasitic wasps, or cultural controls like pruning affected leaves and adjusting conditions so they have a harder time breeding.

With cannabis in particular, you've got to stay on the lookout for whiteflies, because they can hurt both yield and plant health. Catching and wiping them out early can save you from bigger damage. If you're not sure how to deal with whiteflies on your cannabis plants, it's a good idea to get advice from gardening experts or experienced cannabis growers.

What insecticide kills whiteflies on cannabis?

Here are some of the go-to treatments growers use against whiteflies on weed plants:

1. Neem oil: Neem oil is a natural insecticide made from the neem tree. It can disrupt the development and reproduction of whiteflies and other pests. Apply it according to the manufacturer's instructions.

2. Insecticidal soap: Insecticidal soaps, like potassium soap, can be effective against whiteflies. They work by coating the insects' breathing pores and suffocating them. Follow the label and apply it properly.

3. Bacillus thuringiensis (Bt): Bt is a naturally occurring bacterium that produces toxins lethal to certain insects. Heads up: it mainly works on caterpillars, so against whiteflies it's a weak pick; it's more useful as backup if caterpillars are also chewing on your plants. It comes as a powder or liquid; follow the product directions.

What other pests attack cannabis?

Cannabis can be hit by a range of pests that do significant damage to your plants.

Some of the most common pests that go after weed include spider mites, thrips, aphids, beetles and caterpillars. Spider mites are tiny mites that suck sap from the leaves and can cause discoloration and webbing. Thrips are slender insects that usually damage leaves and flowers, causing discoloration and curling.

Aphids form colonies and feed on sap, causing deformed growth and leaving honeydew behind. Beetles chew the edges of leaves and leave holes, while caterpillars eat big chunks of foliage. Watch for signs of infestation and take preventive and control measures to protect your cannabis plants from these pests.

Keeping a clean grow, using biological controls or targeted insecticides and acting fast when an infestation hits can help minimize damage and keep your plants healthy.

If you're just getting started, we recommend signing up for our Successful Grow Course (in Spanish).

Good training makes all the difference!

🌱 Want a permit to grow and transport cannabis in Argentina?

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