Getting Rid of Whiteflies on Cannabis Plants

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Whiteflies on cannabis
Author avatar By Derek LaRose
March 21, 2022
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Seeing tiny winged insects on your marijuana plants? There’s a chance you’re dealing with an infestation of whiteflies on cannabis crops. These pesky intruders can wreak havoc on your flora, but the good news is that it’s easy to keep them away from your precious plants.

Join us to become an expert on dealing with whiteflies on cannabis. We’ll explain what whiteflies are, what they look like, and how their lifecycle works. You’ll also learn how to identify early signs of a whitefly infestation, how to get rid of them, and how to keep them away for good.

Let’s jump in!

Whiteflies on a leaf

What are whiteflies?

Whiteflies are common garden pests that attack various plants, including cannabis. These tiny yet highly destructive insects spread diseases while munching on your flowers, rapidly moving from one crop to the next.

These white bugs typically group in concealed clusters on the underside of a plant’s leaves. They’re diurnal and scatter when disturbed, making it easier to spot whiteflies on cannabis during the day.

More than 1,000 species of whiteflies exist, including the more common ones like silverleaf whitefly, giant whitefly, greenhouse whitefly, and bandedwinged whitefly.

Although they have wings and can fly, whiteflies don’t qualify as a type of fly—they’re more closely related to mealybugs, scales, and aphids. Whiteflies are commonly associated with crops that grow in greenhouses, but they appear in other places too.

These pesky intruders gravitate towards warm and tropical conditions that allow them to multiply year-round. They infest indoor, greenhouse, and outdoor plants in these regions. 

Whiteflies on cannabis plants can’t survive in cold winter weather, so they pose a higher threat to indoor and greenhouse crops in these places. They typically appear during summer when the conditions get hot and humid.

Tip: Never bring new plants into your house without giving them a thorough inspection. If you unknowingly buy flora with a pest infestation, it can quickly spread to other plants in the vicinity.

What does a whitefly look like?

Whiteflies are tiny, softbodied, and triangularlike insects with an average wingspan of 3mm (0.11 in). Their minuscule size makes it challenging to get rid of whiteflies on weed plants without a fine mesh net. Luckily, they often group in clusters that are easier to spot with the naked eye.

These cannabis pests have a somewhat mottled appearance, with four wings covered in a fine wax powder that gives them a dusty look. Most whiteflies are white, but some are also black.

The life cycle of a whitefly

Whether you’re dealing with whiteflies on cannabis or other crops, their life cycle is the same. These insects have a complex development process that consists of five different stages. The entire life cycle takes around 40 days, depending on the temperature.

Here’s a rundown of this process:

  1. Adult whiteflies lay yellow eggs on the underside of a plant’s leaves. 
  2. The eggs turn gray and hatch over the following 5–7 days.
  3. A tiny translucent crawler emerges from each egg, actively searching for a feeding site.
  4. It latches on in a couple of days and rapidly transforms into the sedentary scale stage. A scale is a sucking insect that develops a tough outer skin after enough feeding to protect the growing insect.
  5. Pupation, which is known as the adult development stage, occurs inside the scale. A fully matured whitefly leaves the scale after four days. Adult whiteflies on weed plants can lay as much as 400 eggs and have a life span of four weeks.
Whitefly infestation
Whitefly infestation

Signs of a whitefly infestation on cannabis plants

Spotting whiteflies on cannabis plants is a relatively easy task. Adult whiteflies fly around the crops and form visible clusters on the undersides of the leaves. They create small punctures and yellow dots from feeding that are a dead giveaway, even if you can’t see them.

Gently shaking your plants is an excellent way of quickly checking for a whitefly infestation, as it causes the adults to fly away. Whiteflies generally deposit around 30–40 eggs in a circular shape on the underside of a cannabis plant’s leaves. Use a magnifying glass to check for any eggs.

Whiteflies excrete a sticky substance called honeydew during feeding. If you notice it on your crops, it means they’ve been munching on them for several days. Ants are attracted to the sugary honeydew, so keep an eye out for their presence.

Heavy feeding often rapidly drains the cannabis plant of nutrients and leads to wilting, yellowing, or stunted growth. Eventually, leaves shrivel up and fall off.

It’s incredibly difficult to eradicate whiteflies on cannabis once they’ve settled. Always check the undersides of your marijuana plants leaves, especially during the flowering stage. Whiteflies are notoriously known for feeding on new growth.

Potential whitefly damage to cannabis plants

If left unchecked, whiteflies can wreak havoc on your cannabis crops. Apart from feeding on their sap and weakening the plant’s immune system, they also spread diseases.

Similar to aphids, whiteflies suck on the juice of the plant. This liquid is known as sap and contains high levels of sugar but low amounts of protein.

Whiteflies typically consume more nutrients than they can digest, leading to the secretion of a sticky substance called honeydew. This process allows them to get rid of excess sugar while consuming enough protein. Too much honeydew secretion from whiteflies on cannabis crops can lead to sooty black mold and hamper their ability to photosynthesize.

How to get rid of whiteflies on weed plants

Whiteflies multiply fast, often increasing by up to 200% in a single month. It’s vital to take action as soon as you detect any signs of these cannabis pests. 

You can opt for organic or chemical solutions, but don’t use the latter if your plants have already started flowering—they likely won’t have enough time to recover.

Here are some of the most popular remedies to get rid of whiteflies on cannabis:

  • Sticky fly traps are a cheap and easy tactic. Place them around your marijuana crops to attract whiteflies and leave them immobile.
  • Organic insecticides with rotenone or pyrethrin are also highly effective. Spray some on the leaves and watch the whiteflies scatter.
  • Companion plants like marigolds and basil are a brilliant way of repelling unwanted whiteflies from weed plants.
  • Consider adding natural predatory insects to your crops, like Encarsia Formosa wasps or Macrolophus Caliginosus. These bugs can instantly stop whiteflies in their tracks.
  • Whiteflies can easily build resistance to chemical products, so only use them as a last resort. They’re also more effective when the insects are still larvae.

Whitefly pesticides

Here are some commonly used organic pesticides that can eliminate whiteflies:

  • Insecticidal soaps: This product weakens the exterior shell of aphids without causing harm to your plants (although we recommend avoiding the buds at all times). It leaves no residue and requires multiple applications to eliminate all the whiteflies.
  • Neem oil: A combination of neutral soap and Neem oil is an excellent natural insecticide. Pour both of these products in a bucket of water and use a mister to spray your plant’s leaves gently.
  • Spinosad: This organic product is harmless to plants, people, and pets. Spray it liberally on your leaves and directly on whiteflies. Spinosad is only effective for 24 hours once it comes into contact with water, so don’t use more than you need.
  • Essentria IC3: This product contains various oils and effectively wipes out whiteflies on cannabis plants. It’s active for around eight hours, so daily applications are recommended. 
Adding insecticide to cannabis plants
Adding insecticide to cannabis plants

How to prevent whiteflies on cannabis plants

Whether you’re figuring out how to grow cannabis outdoors or learning the ropes of how to grow cannabis indoors, it’s essential to know how to keep whiteflies from ruining your crop.

Here are some expert tips to prevent a whitefly infestation:

  • Keep your grow room dust-free, well-ventilated, and clear of any insects that could interfere with whitefly predators, like ants.
  • Avoid temperatures above 77℉. The ideal range for cannabis plants is between 68–77℉.
  • Trim and discard any infected leaves to prevent cross-contamination.
  • Introduce predatory insects like lacewings and ladybugs that feed on whiteflies and their eggs. They can also fend off other cannabis pests, like spider mites.
  • Use reflective materials like CDs and foil to deter whiteflies from weed plants.

FAQs

Looking for more in-depth information? Check out some of the most frequently asked questions about whiteflies on cannabis plants:

How do you get rid of whiteflies naturally?

A simple household solution made from water and liquid dish soap is an effective organic remedy for whiteflies. It quickly kills these cannabis pests without harming your marijuana plants. Add one tablespoon of dish soap to a gallon of water and mix well. Spray it evenly on the affected areas and pay extra attention to the leaves and stems.

Will vinegar kill whiteflies?

You can make a homemade insecticide soap using vinegar to eliminate whiteflies on cannabis. Fill a bucket with a gallon of water and add the following ingredients:

  • Baking soda: Two tablespoons
  • Dishwashing detergent: Two tablespoons
  • White vinegar: Two tablespoons

Spray the treatment under the leaves and watch the whiteflies disappear.

What causes a whitefly infestation?

Whiteflies are attracted to nutrient-rich plants that they can feed off. Nitrogen-heavy fertilizers often lead to more frequent infestations.

Dehydrated plants are also more susceptible to whitefly attacks, as they’re typically found in humid regions with high temperatures. These conditions lead to faster reproduction rates and more whiteflies on cannabis plants.

How do you prevent whiteflies?

There are a few ways to prevent whitefly attacks, including:

  • Keep the airflow moving in your grow room and clear any dust regularly.
  • Remove insects that interfere with natural whitefly predators, like ants.
  • Never let the temperature go above 77℉.
  • Always prune infected foliage and immediately throw it away.
  • Add companion plants and predatory insects to deter whiteflies from cannabis crops.
Outdoor cannabis flowers
Healthy outdoor cannabis flowers

The lowdown on whiteflies

Whiteflies are annoying cannabis pests that can quickly turn into a nightmare if you don’t spot them early enough. Luckily, regular inspections of your plant’s leaves can help you detect them and stop them in their tracks before it’s too late.

Remember to avoid extreme temperatures, take preventative measures, and use organic pesticides to eradicate any whiteflies from your cannabis crops.

Don’t forget to buy your marijuana seeds from Homegrown Cannabis Co. and check out our blog for more information about caring for cannabis plants.


About the author: Derek LaRose

Also known as Kronic from The Cannabis Kronicles, Derek LaRose is a young ambitious cultivator and a staple educator for indoor cultivation.