Thrips & Cannabis in 2023: Symptoms, Diagnosis, Solutions

If you are growing cannabis plants, it's important to be aware of the pests and bugs that can threaten the health of your crops. One common thc bug to be aware of is thrips. While they aren't going to kill cannabis plants, they can do a lot of damage. Here is everything you need to know to diagnose and control a thrip infestation.

What Are Thrips?

Thrips are a pest species that feeds on cannabis plants. They will start their life cycle as eggs, before turning into pupae. The temperature will determine how quickly the thrips will develop. In a greenhouse environment, where it is over 77 degrees Fahrenheit (25 degrees Celsius), the insects will develop faster. They will become adults within 13 days.

There are a few physical features that help define thrips, these are:

  • Small size. The typical thrip is between one to one and a half millimeters long.
  • Wings. Though not all species are winged insects, most are. If they do have wings, they will be narrow and have fine hairs.
  • Coloration. Most thrips will be black, brown, or yellow.
  • Rapidly reproducing. The rate at which they breed is what makes a thrip infestation so difficult to control. Thrips can breed 12 times a year.

Thrips eat the sap from plants. They can be found on cotton, vegetables, and fruit plants. But they prefer cannabis plants, where they will thrive. Most commonly, they will be found indoors. This is because of the high temperatures and moist environment created by the greenhouse, which produces the ideal breeding conditions.

There are a few ways that thrips will move around. If there is a small number of them, they will walk between the plants. In larger numbers, they will fly from one plant to the other. Because they are so mobile, it's important to identify and control the infestation early. If you don't, the pests will quickly spread throughout your crops.

Will Thrips Ruin Cannabis?

It's unlikely that thrips will do enough damage to kill cannabis plants. But they can do some serious harm, especially to younger plants. This starts when the eggs are laid, which are laid on plant leaves. When the insects hatch out, they will create small holes. This can leave marijuana plants susceptible to bacterial infection. This can be devastating, leaving plants weakened. In some cases, it will even be enough to kill them.

There are a few other issues that thrips can cause, these include:

  • White spots on the leaves
  • Scarring on plants, from where they sucked out the sap
  • Wilting
  • Damage to the offshoots and flowers
  • Stunted growth
  • Brittle leaves which are caused by the removal of sap.
  • Other cannabis leaf problems

Diagnosing a Thrip Infestation

It's important to spot the signs of a thrip infestation early. If you can do this, it will be easy to control, as they won't be able to establish a strong foothold.

The best place to start looking for thrips is the leaves. These pests will create small marks, which look like thin silvery trails. You can also look for search black marks, which are their feces. You might also spot deformed leaves, or find that they have become more brittle

You might be able to spot them on the plants if you look closely enough. Though when thrips sense movements, they will freeze. Often, they will try to camouflage themselves with the veins of the plants. When you start to search, look at the leaves closer to the bottom of the plants.

The best way to confirm the presence of thrips is to use sticky traps. If there are any of these pests in the area, they will get caught in the trap. You can then more closely examine the insects, finding out what species they are.

How to Combat Thrips

The good news is that there are techniques you can use to get rid of thrips. These can be broken down into a range of categories, these are; mechanical, biological, cultural, and chemical. Let's dig deeper into each of these.


As we mentioned, sticky traps are a good way of catching these pests. They also help you control a range of other insects that might be trying to feast on your crops.

It's also a good idea to clean up the grow tent. There shouldn't be any spaces for the thrips to hide and reproduce.

Where possible, you can try to prune off infected leaves. If the flowers have been affected, you can spray them with neem oil or potassium soap if you catch it early enough. If you are too late, and the infestation has taken hold, you should cut off the bud. It will become too deformed to be useful anyway. This is a good way of stopping it from spreading any further. Remember not to put infected leaves in the compost, where the thrips can breed rapidly.

Another option that may reduce the overall pest population could be reflective mulch. Thrip will use light reflectiveness to find suitable crops. This type of mulch will make your plants harder to see. Silver and gray mulch are the most effective. It should be noted that this technique is best for younger plants, rather than more established ones.


However, if they have already established themselves, you will need to turn to other methods. One of the best is to introduce a predatory species that will eat the thrips. There are a few species you can use, depending on the type of thrip you are dealing with. For example, you can use predatory mites or green laceworms. Wasps, like Megaphragma mymaripenne will eat the larvae before they have the opportunity to become adult thrips. While this can be a good way of controlling the population, studies show that this measure alone is unlikely to adequately eliminate thrips.


There are some simple steps you can take to get rid of thrips. Proper cultural practices can also help to strengthen the plant, preparing it for pest pressure by improving its health and increasing its natural tolerance for stress.

Proper watering, which we talked a bit about in our yellow cannabis leaves article, can help to accomplish the same goal.  Proper watering practices can reduce the impact of natural stressors on the plant and help to reduce physical symptoms when problems arise.

It's also best to be vigilant in your grow tent. If you catch the infestation early, you can put the plant into isolation. This will stop it from spreading, helping you limit the damage.

Lastly, it can help you maintain the correct growing conditions in the greenhouse. The stronger the plants are, the less susceptible they are to thrip damage.


Often, though, to truly get rid of thrips you'll need to turn to chemical solutions. There are a few options that you can explore. Though you should make sure that you choose something that won't harm humans or pets. Plus, you'll need to avoid anything that can harm friendly insects that are helping to control the thrip population.

If you want to get rid of thrips, here are some of the options you can explore:

  • Potassium soap
  • Neem oil
  • Diatomaceous earth
  • Spinosad

You'll need to make sure that you are applying the spray to all parts of the plant. Cover the flowers, leaves, and buds. Remember to spray the soil, as this is where the thrips might deposit their eggs. You might need to spray the crop a few times before you can eliminate the thrips.

Try to spray in the morning or evening. This is when the thrips feed. When activity is highest, the exposure to the chemicals will be higher.

If you are still finding it hard to get rid of this pest, you might need to turn to an insecticide. Though this should be used as a last resort, because of the toxicity involved.

How Do I Get Rid of Thrips in my Grow Tent?

While you might have removed thrips from the plant, your work isn't finished yet. You need to check the grow room, to make sure that there is no chance that they will return. The good news is that there are a limited number of ways that thrips can infect cannabis plants.

First, you need to make sure to check all the shoes before letting people into the grow room. If they were in an infected area, thrip eggs might have hitched a ride in some infected soil at the bottom of their boot. Since thrips can reproduce without mating, it only take a few adult individuals to produce a large population.

It's also important to consider the grow tent set up. Make sure that there aren't any ways that thrips will be able to enter the room.

If you still can't eradicate the insects, they might have gained foothold in your grow tent. In this case, you might need to remove the cannabis plants and release a smoke bomb. This should kill the thrips.

Preventing Thrips

There are a few simple things you can do to prevent thrips. Let's look at some of these.

First, you should remove weeds from the nearby area, especially if your crop is outside. They will attract thrips, particularly during the summer months.

It's also important to remove any debris from your garden quickly. This can provide a place for thrips to breed and lay larvae. If it isn't infected, you can add the garden waste to your compost pile. This will allow you to release the nutrients.

Some thrip species will lay their eggs in the soil, rather than putting them beneath leaves. This makes the signs of an infestation more difficult to identify. Because of this, it's a good idea to change the substrate you are using between each crop cycle.

It's best to make stop thrips before they can take hold. Because of this, you should inspect new plants before bringing them into your grow room. If there are signs of an infestation, place the marijuana plants into isolation until you have it under control.

Finally, it's a good idea to leave some sticky paper around the lab. In a healthy lab setting, there shouldn't be any signs of thrips or any other type of insects. So, if you start to detect them on the traps, it can indicate that you need to step up your attempts to get rid of these insects.

Additional Defense

Although your priority should be to control pest issues at the root when problems arise, it's important to note that you can also tackle important aspects of the problem at the plant level as well. Like finding out the common causes of yellow cannabis leaves.

Much like how proper eating habits can improve a person's immune system and overall health; proper fertilization can improve your crops' natural defenses and decrease the likelihood of physical symptoms that would impact your harvest. 

NorCal Nutrients carries both organic and hybrid lines of fertilizers to help you reach your best yields and healthiest crop to protect against pressures like thrip damage. Check out our shop here to find the best product for your plants and learn about organic vs inorganic fertilizers.


When you are growing cannabis plants you need to pay attention to the potential pest species that might be damaging your crops. While thrips are unlikely to kill the crop, they will reduce yields. Even worse, they are fast moving, quickly infecting an entire harvest. Thankfully, there are a few simple steps you can take to prevent thrips, stopping the problem before it can get started.