Cannabis pests- Whiteflies

The whitefly (Bemisia argentifolii), an insect that many (Cannabis) cultivators have to deal with, which sometimes is a hell to do so. Like the name says, it’s a white type of fly that is often found around and under the leafs of your plant. To grow healthy plants, it’s definitly required to ward them off and keep them away as they are able to destroy a cannabis plant. In this article we will explain how to detect, avoid and treat white flies on your cannabis plants!


In this article:


How to recognize Whiteflies?

What do they look like?

Whiteflies are well known all over the world and attack all kind of crops. Too bad they love cannabis plants too. They look a bit like very small, white moths with yellow/white bodies and are around 2MM’s long. Their behaviour is very similair as the “spider-mite” and they can be found under the leafs (There they eat vital nutrients from the plant).

As you can see, whiteflies have big wings and looks a bit like a moth. Adults often live on the upper side of the leaf while new-borns mostly hide under the leafs.

Another way to recognize a whitefly infestation is by looking for it’s eggs. Whiteflies could lay up to 400 egg’s at one time, so finding them shouldn’t be hard. The egg’s of a whitefly are mostly find hidden under the leafs, so make sure you keep a close watch on them! They are grey/yellowish and will hatch in about 1 week.

 

Lots of Whiteflies hiding under a leaf. These amount of whiteflies often lay lot’s of egg’s which will hatch in +- 1 week. This way, a infestation will spread quickly.

Signs of whiteflies

Because of their white colour and bigger colonies, it’s nod very hard to spot certain sign of a whitefly infestation. They often fly around your plants (shaking the plant will help seeing them fly) and their eggs can be found under the leafs.

Next to that, there are other signs that your plant is being attacked by whiteflies. First of all you need to know that Whiteflies suck out the nutrients out of the leaf by puncturing them. This will leave white small spots all over the leaf. With lot’s of Whiteflies, a leaf can eventually turn yellow and die. So even without seeing flies, you can recognize them by these spots.

Another sign of Whiteflies is finding something called: “honeydew”. This is a sweet, sticky substance that Whiteflies produce because they often consume way more then they are able to digest. This is also common to find on plants infested with Aphids. Watch out for this substance because “black sooty mold” loves to us it as a grow medium!

A whitefly sucking nutrients out of a leaf by puncturing them. This leaves small white spots all of the leaf which can be detected by the grower.

How to avoid Whiteflies?

Before you need to think about treating a Whitefly infestation, you should always try to avoid it first (like most pests). It’s always easier to prevent an infestation, then to treat one. Especially in this case because a Whitefly population is able to grow pretty quickly.

To prevent whiteflies from coming to your plant, you first need to think about environmental factors. These flies won’t visit a place they don’t like so by creating an environment thats not interesting for them, you will keep them away. Let’s take a look at thise factors:

Temperatures- Whiteflies love high temperatures and hot weather. Make sure your temps won’t reach higher then: 68-77ºF or 20-25ºC. LED lights and enough fans could help you with this. Once there are Whiteflies on your plant, try lowering the temp a few degrees.

Air circulation- An important step for most cannabis pests is taking care of a good working air-circulation. This helps with temperatures and humidity problems which leads to an increased chance of whiteflies coming to your plants.

Natural predators- Whiteflies mostly avoid plans that contain natural predators of the Whitefly. So a great idea is leaving these bugs on your plant as long as they don’t harm your plant (Which most insect predators won’t). A great example are ants, they prey upon Whiteflies and aren’t harmfull to your plant at the same time.

Multiple Whiteflies feasting on a leaf.

By creating an envivonment that contains the factors above, you decrease the chance of a Whitefly infestation drastically. Next to prevention, this is also the first step for a treatment which we will talk about more!


How to treat a Whitefly infestation?

Once your are too late and not able to avoid a Whitefly infestation, it’s time to look at the possibilties you have to safe your plants. First of all, you need to act as quickly as possible. Once you have detected the first signs, it time to start your treatment!

The first thing you should do is changing the environmental factors like described above. Even if there is already a full infestation! After that, it’s an great idea to remove the most infected leafs. Just cut them off and put them in an air-closed bag to avoid them from spreading to other plants.

Some whiteflies and whitefly egg’s on a leaf. Whitefly egg’s are very hard to remove so hosing down your plants won’t help. Infected leafs lik this one should be cut off.

At this point, it might look like you removed most of the Whiteflies. However, there are always some egg’s and flies left that you didn’t see. If you want to get rid of all whiteflies you have to look at other remedies like: Organic insecticides or natural predators

Natural predators/enemies:

There are multiple other bugs and insects that love to prey on Whiteflies. Think about: Ladybugs, predatory mites, ants and lacewings. It’s an great idea to add these kind of bugs to your growroom as they control lot’s of different pests like spider-mites, Aphids and other small insects. We recommend to use Ladybugs! These can be bought in your local gardening store or on the internet.


Organic insecticides/pesticides:

Another great way to fully getting rid of Whiteflies is using some organic (Safe for consumption) pesticide/insecticide. We have listed a top 3 of proved products you can use:

Essentria IC3 is a pretty common and effective treatment for multiple pests. It is often described as “bed-bug killer” en despite it’s so effective, it’s very safe for humans and 100% organic. It should be sprayed evenly all over the plant. The only downside of this product is that it only works for +- 8 hours so it should be used regularly (or in combination with another product).


Spinosad is an 100% natural and organic pesticide that will effect the Whitefly nervous system and eventually kills it. Only contact or ingestation with Spinosad is enough for an whitefly to die. You should spray this product all over the plant and anywhere you see the whiteflies (especially under the leaves). Spinosad products often only work for 24 hours, so respraying the plant is necessary.


Spinosad is made from a special fermentation of soil bacteria called: actinomycete Saccharopolyspora spinosa. This organic product might not work as aggresive as other pesticides but is still very effective for Whiteflies and extremely safe for humans, pets and plants. Another great thing for outdoor/organic growers is that this product is specifically harmfull for whiteflies and less for other insects. So you can combine this spray with ladybugs.


  • Neem oil

Special oils are getting more populair for treating pests on cannabis plants. In the case of Whiteflies you could use something called “neem-oil”. This works very effective but it has some downsides compared to the other pesticides. First of all the smell. Neem oild could contain an intensive smell that you will transfer to the plants surface. So never get any neem-oil close to your buds (Try to avoid neem oil on flowering plants in general).

Another issue is that there are some researches that suggest that Neem-oil might be harmfull for humans. So always be carefull when using this product! That being said, Neem-oil is 100% natural and very effective for many pests and molds! Neem-oil is available on multiple websites and in your local gardening stores!