Thrips on Houseplants: 6 Top Steps to Treat (and prevent)

Some of the links in this post may be affiliate links.

Thrips are arguably the most frustrating and persistent houseplant pest that you will encounter. I know the struggle all too well, so in this post, I will cover everything that you need to know about how you can practically and effectively deal with thrips on houseplants.

I’ll touch on the lifecycle of thrips, which is really important to understand so that you can effectively treat for them. This is not a pest that you can spray once and be done with it. This goes for many pests, but particularly thrips.

I also have some photos showing thrips damage so that it can help you correctly identify the problem. I’ll also recommend some products that I like to use to manage and eliminate thrips on houseplants.

I’ve learned that all it takes is ONE female thrips in order to cause a big infestation in your houseplants. There are about 6,000 species of thrips, and many will devastate commercial crops, but only about a dozen or so appear on our houseplants.

Also, before we continue, I’d like to mention that the singular and plural is…thrips. One thrips and two thrips are both correct…but in the end, we want ZERO thrips, so let’s get into it.

WHAT ARE THRIPS?

Thrips are very small pests and often times, you will see the damage that they cause before you actually notice the pests themselves. Most thrips are only about 1mm long or so and are very narrow.

Most of the adult thrips that I’ve seen are black in color, but they can also be other colors as well. Immature thrips, called nymphs, will be lighter in color.

Here is a closeup of an adult thrips:

Here are some nymphs that I found scattered all over on my Peperomia polybotrya, or Raindrop Peperomia. Note the pale color:

THRIPS DAMAGE ON HOUSEPLANTS

How do thrips damage your plant?

Thrips basically pierce holes into your plants (leaves, flowers, etc.), and then they literally suck out your plant’s sap and juices.

The resulting damage will typically look like silvery or brownish marks on your foliage. Some species of thrips even leave dark deposits (which is basically thrips poop!) Gross.

Be sure to also inspect the bottom of your leaves as well. In the photo below, the top of the Anthurium leaf looked fine, but take a look at the thrips damage at the bottom.

Flowers and leaves can even develop silvery streaks, and the new growth or growing points of your plants can seem gnarly and contorted.

Here is some thrips damage on an Oxalis triangularis leaf.

Female thrips will insert their eggs into your plant’s foliage, flowers and stems. Then the eggs will hatch and the juvenile thrips, called nymphs, start feeding on your plant.

In most species of thrips, the fully grown nymphs will often drop to the soil where they will undergo the pupal stage. After this part of the lifecycle, they will then transform into adults and fly back up to your plant and perpetuate a cycle of destruction.

Under the right temperatures and conditions thrips can go from eggs to adult in as soon as 2 weeks.

One of the reasons that thrips are so difficult to manage, is that even if you use an insecticide spray on your plant, it will kill any nymphs and adults, but the eggs will not be affected since they are buried in your plant’s tissue.

Read this post in its entirety because I will discuss the best ways to treat thrips on houseplants so that you can enjoy the most success.

WHERE DO THRIPS COME FROM INDOORS?

Thrips can come from a number of places including:

• If you’ve summered your plant outdoors, they could have attacked your plant and you could have proceeded to bring thrips indoors when you’ve brought your plant back inside.
• Thrips could have been lurking on new houseplants that you’ve purchased or brought home. They are often very difficult to see, especially at the beginning of the infestation.
• Among the most susceptible houseplants to thrips are: Aroids (Monstera, Alocasia, ZZ Plant, and many more), palms and Calathea.

HOW TO GET RID OF THRIPS ON HOUSEPLANTS

For plants that have suffered a severe infestation, it may be best to just throw away the plant. Unless it’s something rare or special to you, often times, it is not worth fighting the battle if the plant is severely infested.

Please note that some plants can be sensitive to insecticidal soap, including some succulents, ferns and begonias.

If you are using insecticidal soap for the first time on a certain plant, test it first. Spray a leaf or two, and wait for 24 hours. If everything looks fine, go ahead and spray the entire plant.

Keep your plants out of direct sun when you spray them while the plant is still wet.

If you’ve noticed that the leaves had an adverse effect, try another spray. Always read the label carefully as they will often list which plants the product is not safe for.

Here is the process that I use to treat for thrips:

1. Remove heavily infested leaves/flowers

Cut off or trim away any heavily infested plant parts. Place them in the trash, tie the bag up tightly and discard.

2. Wash down your plant

Take your plant to a sink or shower, or even outdoors if you’d like if it’s warm enough. Rinse off your entire plant as thoroughly as you can, including the undersides of the leaves.

This will help knock down the population of thrips on your foliage.

3. Spray with insecticidal soap

Next, after the plant is dry, I like to use a good insecticidal soap to spray on your plant. Cover all surfaces the best that you can, including the undersides of the leaves. Leave no surface unsprayed.

If you have any flowers that seem affected be sure to spray those as well (or just snip them off and throw them away).

The insecticidal soap will kill any nymphs as well as any adult thrips that come in contact with the spray.

Bonide makes a good insecticidal soap that you can use. Insecticidal soaps are considered to be non-toxic to humans and pets.

4. Apply a systemic insecticide

Like I mentioned earlier in this post, any type of insecticide spray that you apply will not work on the thrips eggs because they are found under the surface of the leaf inside of the plant’s tissue.

This is where a systemic insecticide comes in. You can sprinkle the recommended amount of systemic insecticide into your soil and water it in.

The plant will then take up the insecticide from the roots. When thrips feed on your plant, it will essentially poison them and thus help stop the lifecycle from perpetuating.

I use Bonide Systemic Houseplant Insect Control for this purpose. Use only as directed on the label and apply at the recommended frequency.

This is available for home use in the U.S., but apparently is not available in some countries like Canada and others.

Using a systemic insecticide in combination with diligent spraying with insecticidal soap is very helpful.

If you don’t want to use a systemic or can’t obtain any, you can still treat with insecticidal soap but it will require a bit more diligence and multiple, weekly applications over a period of several weeks.

5. Use sticky traps to capture adult thrips

You may already be very familiar with yellow sticky traps used to capture adult fungus gnats. They will also work on thrips!

Place your yellow sticky traps in the pot of your infested plants and monitor them as they catch your thrips.

Blue sticky traps are particularly attractive to thrips, so you can use these as well. You can even use them in combination with yellow sticky traps. Place a yellow stick trap at the base of your plant near the soil, and maybe hang a blue sticky trap right above your plant.

Capturing as many as you can on the sticky traps will help knock down the population since they will no longer be able to lay eggs on your plants.

6. Repeat steps 2 and 3 weekly

Don’t skip this step! This one is critical! It is important to repeat step 2 (washing down your plant) and step 3 (spraying with insecticidal soap) weekly, even after you don’t see anymore new damage from thrips.

Try and be diligent and do this weekly because there are always thrips in different stages of their lifecycle, so this is necessary to kill as many thrips as possible.

Lastly, there is one practice that I wanted to mention that I’ve heard many plant parents do. Some people will wash off all the soil from the roots and repot into fresh potting mix.

I would recommend not taking this approach for the following reasons:

• You can still have thrips dropping from the foliage above into your fresh soil, thus negating the reason you changed the soil out in the first place. This was stated by Keele University professor of entomology William Kirk, who also added that thrips sometimes pupate on the plant, but usually it’s on the soil or surface of the soil.
• Removing all of the soil from your plant will also unnecessarily shock your houseplant. Stressed plants will be even more prone to further pest attacks.

PRODUCT LIST

To summarize, here are the products I recommend:

• Bonide Insecticidal Soap
• Yellow sticky traps
• Blue sticky traps
• Bonide Systemic Houseplant Insect Control

PREVENTING THRIPS

What are some things that you can do to prevent thrips from attacking your houseplant collection?

• Give your plants weekly or biweekly showers if you can. This will not only knock off any thrips that happen to be on your plants, but it will also keep your plants free of dust and allow them to be healthier.
• Inspect any new plants that you are purchasing very closely and avoid bringing home any potentially infested plants.
• When you do bring any new plants home, it is a good idea to quarantine the plant for 2-3 weeks if you can. Place your new plant away from other plants while you monitor.
• Increase humidity preferably with a good humidifier. Thrips (as well as spider mites) tend to prefer drier air, so providing a more humid environment will help to deter them.
• Inspect your plants regularly! It is much easier to treat a pest issue when caught early.

RELATED CONTENT

If you’ve enjoyed this content on treating thrips on houseplants, check out my other blog posts on dealing with other pests on your houseplants:

• Spider Mites
• Scale
• Fungus Gnats
• Mealybugs

Lastly, if you’d like to hear more details about thrips (from entomology professor William Kirk) check out Jane Perrone’s excellent podcast (On the Ledge) episode where she interviews professor Kirk talking about thrips.

FREQUENTLY ASKED QUESTIONS

Have you had thrips on your houseplants? I’d love to hear your struggles and how you’ve overcome them. Comment below!