How to Control and Prevent Whiteflies?

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Added 07 July 2023

Is your cannabis plant home to tiny moths? Be warned, these “tiny moths” may not be moths but whiteflies — a notorious type of pests that look like tiny moths but can significantly affect your cannabis plant’s health.

Whiteflies are one of the most common pests that affect cannabis plants, and if you don’t take the right measures to prevent and control them, you may eventually lose your plant. In this article, learn how to control and prevent whiteflies on cannabis. 

What are Whiteflies?

What are Whiteflies?

You may not have heard of whiteflies in your biology class, but as a cannabis grower, you must know as much as you can about these notorious pests. These white little insects are hemipteran in nature, belonging to the Alecyrodidae genus, and they are known to infest various plants, including your beloved cannabis plant. 

These insects look like miniature moths and they harm your plant by sucking out the sap, which can lead to various problems in the plant. They act as parasites that suck essential nutrients from the plant, leaving your plant to starve or face deficiencies. And even though they are smaller than 1.5mm, they can cause havoc to your plant if you don’t deal with them on time. 

Whiteflies aren’t a single species of insects, though; there are over 1,500 types of whiteflies, but the most common one that attacks cannabis plants is the greenhouse whitefly, scientifically known as Trialeurodes vaporariorum. This type of whitefly is known for multiplying rapidly and being difficult to get rid of. 

Like many other insects, whiteflies also live a fast life. A single adult can lay up to 300 eggs in its lifetime, which can hatch within six days. Once they hatch, they go through four different developmental stages, which take around a month. After the four stages, they become mature and start reproducing quickly, and the cycle continues. 

One of the most common causes of whiteflies is high temperatures or relative humidity, especially in greenhouses or grow boxes. So, if you live in a humid or warm region, you should especially be worried about them. 

What Do Whiteflies Look Like?

What Do Whiteflies Look Like?

You need to be wary, but how do you keep an eye out for them if you don’t know what they look like? We’ve got your back. Although whiteflies vary in what they look like, with the biggest difference between species being the number of wings — some have two and others four — they still share many similarities. 

Some of the identifying features of whiteflies are:

  • Female whiteflies’ length is between 1 to 1.5mm while the males are smaller
  • Their wingspan is about 3mm
  • They have two antennae and two eyes
  • They possess 12 legs, two of which are hidden under the wings
  • Generally, whiteflies are white in color — thanks, Captain Obvious — but sometimes they can be of different colors
  • It may appear that they are covered in fine wax powder

Yes, whiteflies are tiny. So while you may spot them when you inspect your plants for bugs, you should also be aware of other signs and symptoms of whiteflies on cannabis, which is explained in the next section.

What are the Signs of Whiteflies on Cannabis?

What are the Signs of Whiteflies on Cannabis?

Whiteflies may be small but their impact is big, not in a good way, and they leave a large footprint on your cannabis plant during an infestation. So, what are the signs of whiteflies on your cannabis plant? Here are some of them.

  • You’ll spot them walking around on your plant 
  • You’ll see patches of eggs on the underside of the leaves — often in a spiral or arc pattern
  • Your leaves may develop yellow or translucent marks due to their munching 
  • They produce a sugary waste called honeydew, which can also attract sooty mold 
  • You may also find ants crawling around on your plant that come looking for honeydew 

How to Prevent Whiteflies on Cannabis Plants?

How to Prevent Whiteflies on Cannabis Plants?

The best way to deal with whiteflies is to prevent them. While you can’t avoid them entirely, you can still take steps to prevent them to a significant extent. Follow these steps to prevent whiteflies from attacking your cannabis plants.

1. Keep Your Grow Room Clean and Sanitized

Regularly inspect your cannabis plants for any signs of whiteflies. Look for the tiny white insects on the undersides of leaves or flying around the plants. The first step in preventing not only whiteflies but almost every other pest is to keep your grow room or greenhouse clean and sterile. 

Pests are generally attracted to places that are full of dust and debris, which is inviting to them. And once one pest makes its way into your grow room due to debris, many others follow, so keep your grow room clean and prevent them to a great extent.

If you notice any leaves heavily infested with whiteflies, promptly remove them to prevent the spread of the insects. Dispose of the infested leaves away from your garden area.

2. Keep Your Grow Room at the Right Temperature and RH

As mentioned earlier, whiteflies are attractive to spaces with high temperatures and relative humidity. So, make sure your grow room remains between 68°F to 77°F (20°C to 25°C) and if you are still worried about whiteflies, you can bring the temperatures further down, under 77°F or 25°C.  

Also, keep the humidity in check, as per your plant’s grow room, and take measures to keep the air within your grow room or greenhouse fresh. Set up oscillating fans and vents along with an exhaust fan with negative air pressure. 

Most importantly, maintain proper airflow as whiteflies are more likely to settle in areas with still air. To discourage their presence, ensure proper airflow around your cannabis plants. Consider using fans or creating ventilation systems that provide a gentle breeze. The airflow will make it challenging for the whiteflies to land and establish colonies on your plants, reducing the risk of infestation.

3. Use Neem Oil as a Preventative Measure

Neem oil is one of the best insecticidal sprays for cannabis plants; it is effective against almost all pests and completely organic and safe for your plant. Plus, it’s so cheap and easy to make it almost renders every other pesticide useless. Neem oil not only kills insects but its pungent odor also keeps other pests away.

So, to prevent whiteflies from coming onto your cannabis plant, it is recommended that you spray down your plant with neem oil at least once every 20 days. However, do not spray on the buds as it can leave a nasty aroma and aftertaste on your buds, affecting their quality and even potency. 

4. Quarantine New Plants

When you introduce new plants to your cannabis garden, it's best to quarantine them for a period of time. Quarantining allows you to observe the plants for signs of whitefly infestation or other pests before integrating them into your garden. Keep the new plants separate from your existing cannabis plants for at least two weeks. During this time, closely monitor them for any signs of whiteflies or other pests. If you detect an infestation, take appropriate measures to treat the affected plants before bringing them into the main growing area.

5. Practice Crop Rotation

If you grow cannabis outdoors, practicing crop rotation can help disrupt the life cycle of whiteflies and reduce their population. Whiteflies can overwinter in the soil, so by changing the location of your cannabis plants each year, you make it more challenging for the insects to persist. Additionally, rotating crops helps prevent the buildup of pests and diseases in the soil, promoting healthier plants.

6. Use Sticky Tapes Around the Space

Lastly, hang yellow sticky tapes all around your cannabis grow room. These sticky tapes act as traps that attract errant whiteflies, which get stuck to the tape as soon as they make contact with them. Remember, sticky tapes aren’t the most effective preventative measure but can help you when used with other methods recommended above. 

How to Eliminate Whiteflies from Cannabis?

How to Eliminate Whiteflies from Cannabis?

Whether you’ve taken the right preventative measures or not, whiteflies can still make their way into your grow room and attack your plant. If this happens, don’t panic. While whiteflies are difficult to deal with, but getting rid of them is not an impossible task. Follow these steps to get rid of whiteflies from your growing room.

1. Prune and Hose Down Your Plant

If you’ve spotted whiteflies on your cannabis plant, the first step you need to do is prune your plant followed by giving it a thorough wash. So, get your pruning scissors and cut off any leaves that have been infected. 

Once you have pruned the infected parts on your plant, the next step is to hose down the plant with clean water to remove any leftover whiteflies and their eggs. Spray them down with a hose with good pressure since their eggs can be stubborn to remove. 

2. Introduce Beneficial Insects

If the situation isn’t severe, you can even employ beneficial insects to prey on whiteflies. You can purchase beneficial insects like ladybugs from your local gardening store; simply get a batch of them and let them loose in your grow space. They will hunt down and kill all whiteflies in a few days.

Some other natural predators you can use are:

  • Cales Noacki, a type of small wasp that preys on whitefly larvae
  • Encarsia formosa, a small fly that lays its eggs in whitefly larvae 
  • Macrolophus Caliginosus preys on whiteflies of all shapes and sizes 

3. Use Neem Oil

Coming back to neem oil, it not only acts as an excellent preventative measure but is also quite a potent insecticide. No wonder it’s a favorite among cannabis growers. If your cannabis plant is suffering from a whitefly infestation, you need to use neem oil as a foliar spray. Aim and spray neem oil wherever you see whiteflies. 

If the infection is severe, you can even use a neem oil-soaked sponge to wipe down the entire plant. Be gentle and use diluted neem oil, and don’t forget to wipe the undersides of the leaves to clean up the mess left behind by whiteflies. 

4. Insecticidal Soap

If you can’t use neem oil, you can even use insecticidal soap to eliminate whiteflies on your cannabis plant. Such an insecticide works in targeted termination, so use them whenever you spot a whitefly on your cannabis plant.

You can make insecticidal soap at home by adding 10 ml of regular soap with a liter of water. If you use store-bought insecticidal soap, be sure to read the instructions carefully before using it. 

Remember, whitefly control often requires repeated treatments to break its life cycle and achieve long-term eradication. Monitor your cannabis plants regularly for any signs of whitefly resurgence, and continue with your chosen control methods as needed. Be patient and persistent, as it may take several weeks to completely eliminate the whiteflies from your garden.

Summary: How to Control and Prevent Whiteflies?

Whiteflies are annoying pests that can quickly take over your cannabis plant and suck essential nutrients from the plant. This can cause nutrient deficiencies in your plant, and they excrete honeydew that can invite various other harmful pests to your plant. 

So, take the right steps to prevent whiteflies from attacking your cannabis plant: keep your grow room clean, maintain the right climate, and use neem oil and sticky tapes. If they still make their way into our grow room, prune and hose down the plant, introduce ladybugs and use neem oil to finish them off. 

Whiteflies are notorious but nothing a little prompt action and the right product can’t fix. So, use this guide to identify, prevent, and get rid of whiteflies from your garden. 


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