When you have colonies of thrips infesting your plants, it can be a nightmare trying to get rid of them. It’s not impossible, but time is of the essence! To control thrips immediately, here are the ways you can finally exterminate them from your plants once and for all.
The most effective way to eliminate thrips are physical removal, hosing, predatory insects, and the application of organic insecticides like neem oil, castile soap, and alcohol. Chemical pesticides can be used but are not recommended, especially for flowering plants or edible crops.
It can be heartbreaking having to watch your plants be damaged and even killed by thrips. But I’m here to save you from all that trouble! Read on as I give you a guide that you can use to effectively control and eradicate thrips.
Table of Contents
- 1 1. Physical Removal
- 2 2. Hosing
- 3 3. Predatory Bugs
- 4 4. Neem Oil
- 5 5. Castile Soap
- 6 6. Rubbing Alcohol
- 7 What Are Thrips?
- 8 4 Signs Your Plants Have Thrips
- 9 How Do Thrips Enter the House?
- 10 7 Ways to Help Prevent Thrips
- 11 What’s the Difference Between Fungus Gnats and Thrips?
- 12 FAQs
- 13 Summary of 6 Ways to Exterminate Thrips on Plants
- 14 Sources
Physically remove thrips from plants by shaking or wiping them off. This method of control is straightforward, but it is very unlikely to completely eliminate the thrips population.
This may be the easiest and most hassle-free method of handling these insects. Plants that are infected can be simply wiped clean of thrips. They can also be gently beaten or shaken over a piece of paper or fabric, so that the thrips may fall out of your plant.
However, even if you were to do this religiously, you probably wouldn’t get rid of all the thrips. Because some thrips live in the soil and eggs are laid inside the leaves themselves, some gardeners prefer to manually cut off all the infected leaves and squish any bugs they see.
Take care not to accidentally transfer the thrips from one plant to another, and be certain every tool used in this process is spotless and sanitized.
More importantly, keep in mind that there really are no one-and-done treatments. These methods are best done on a regular basis to prevent thrip infestation! Luckily, though, they’re relatively simple, so let’s go over the rest.
Plants infested with thrips can be hosed down and effectively stripped free of any insects that are physically lodged. This method will not kill all the thrips, but is useful in controlling the thrips’ numbers. Using a soap solution while hosing helps kill thrips at all stages.
If there are too many thrips for you to shake out, this is a good option. Take the affected plants and carefully but firmly hose them completely down with cool water.
The goal here is to try to use the direct stream of water to wash off as many thrips as you can.
Hosing down affected plants won’t eradicate all the pests entirely, but this can be done often to keep their population down.
If you use any type of soap solution on the leaves, you can pair it with this method of hosing afterward to help in both rinsing the plant, and knocking off any remaining thrips, creating a very effective method of handling thrips. But more on this in a bit!
Natural predators such as Stratiolaelaps and cucumeris mites can be released to help control colonies of thrips in the long term. Biological control, however, may not be permitted in some regions and may not be a viable option for those with sensitive animals.
Depending on your area and country, you may not be able to use biological control for household usage, so check if this is possible first. This method may not be an option for those in Canada.
A fair bit of warning: You may also be unable to use this if you live with other people or have very sensitive pets.
Helpful predators like Stratiolaelaps mites (S. Scimitus) and cucumeris mites (A. Cucumeris) are microscopic, and each mite can eat up to 2-3 thrips per day, providing easy control for up to 28 days or more.
This method is better utilized as a preventative measure, but it can still be used for active infestations.
Neem oil can be used to exterminate thrips using a variety of different treatments such as sprays, soil drenching, and deep soaking. However, it is not advisable to use this formula without confirming the plant is tolerant of the solution. Hence, a leaf test is recommended before application on the affected plant.
Neem oil is a great choice and can help in suffocating adult thrips by smothering their openings with oil and blocking them, preventing them from breathing entirely.
Depending on how severe the attack is, you can use this treatment in a variety of different ways. This would include, but is not limited to: sprays, soil drenching, and deep soaking. Apply the treatment to one leaf first to see if there is any burning.
>>> You can find a more detailed guide in our article on using neem oil.
For 1 gallon (3.79 liters) of water, you can mix around 3 tablespoons of pure neem oil and 5 drops of soap. I recommend castile soap to be safe. You can use this to spray on individual leaves, or even drench or soak badly infested plants in this.
This product below, which you can find on Amazon, is what I normally recommend.
Castile soap helps eliminate soft-bodied pests such as thrips. But it must first be tested before treatment is fully applied to affected plants.
Castile soap is completely organic and while it isn’t an insecticide, the fatty acids in it can be incredibly helpful in fighting off soft-bodied insects like thrips.
You can mix around 2 teaspoons of castile soap to around 1 quart (0.95 liters) of water and use this as a spray.
But some plants are more sensitive to soap than others. So be sure to test this first before proceeding with treatment. You may have to experiment a bit with the dilution for different plants.
Rubbing alcohol can be used to eradicate thrips, but only when properly diluted. Application is commonly done with sprays and spot treatment. Tests must be done beforehand to confirm whether the plant will not be burned.
Your everyday rubbing alcohol can be used to help kill thrips, but this is incredibly powerful and must only be used when it is diluted. If you have 95% strength alcohol, decide how much of the solution you need and mix at least 1 part alcohol to 1 ½ part water.
I have used this before, and it is effective when used as a spot treatment or as a spray.
But take care not to leave plants treated with this out in direct sun, as the leftover alcohol treatment could potentially lead to the foliage burning under the sun and may kill the plant. Once more, test this solution on a leaf beforehand to make sure it does not harm your plant.
Take note, however, that thrips are quick to develop resistance. Whatever pest management system you decide to use, I highly recommend using multiple and making long-term rotations regularly, to help prevent the thrips from building resistance.
While chemical pesticides can be used, this may be damaging and is not recommended for plants with flowers or plants you intend to consume.
Thrips are sap-sucking insects that typically only grow up to 1-2 millimeters long. Their bodies are similar to lobsters, and they have hairy, fringed wings. Thrips are also known carriers of tospoviruses, which are incurable infections that can kill plants.
Originally from New Zealand, thrips are tiny insects that only grow a few millimeters long. There are over 6,000 species, but you can typically identify them by their fringed wings, and their resemblance to lobsters.
These pests suck and feed off of the plant’s nutrient content from the leaves, often favoring younger plants with tender shoots and leaves.
They won’t immediately kill your plants, but they can damage it severely and may even act as vectors for tospoviruses. Tospoviruses, like the tomato spotted wilt virus, are plant infections that are usually not curable, and can become a serious threat to your plants.
Thrips have a five-stage life cycle that goes in the order of egg, larvae, prepupal, pupal, and adult. Once the eggs hatch, larvae will fall into the soil and finish development, before finally emerging as adult thrips.
Thrips can survive in different habitats, but they frequently thrive in warm weather. Their life cycles consist of five different stages that only take roughly 16 days to complete:
Saw-tailed thrips use their serrated egg-laying tubes—ovipositors—to cut holes into leaves. These allow adult female thrips to lay eggs inside the holes, laying as many as 50-200 eggs each time.
These insects do not need to mate to create eggs, and unmated females can still lay eggs. However, these unmated female thrips will only produce males. Females that have mated with their male counterparts will produce both female and male thrips.
After 6 days, the eggs hatch and turn into larvae, moving in the leaves to feed off your plant for another 6 days. Larvae, creamy and smaller than adults, are often seen in colonies.
After they feed, these baby thrips then drop off of leaves and finish their next two stages in the soil for an average amount of 4 days.
Once they finally develop wings and grow into adults, they will fly up from the soil and begin their search for new areas to feed and lay eggs, repeating the cycle.
In warm weather, thrips can complete this entire life cycle in just under 2 weeks.
On average, there are 4 signs that indicate the presence of thrips on plants: 1) mottled leaves with black specks, 2) silvery appearances, 3) distortion and discoloration, and 4) the appearance of thrips themselves as black or white insects.
Because of how small they are, you may not even notice these pesky insects until the infestation is severe. So here are some of the signs your plants have thrips, and what the damage done by thrips typically look like.
This is the easiest tell-tale sign of thrips. Their feces will look like small, black dots and may not look suspicious at first. But if infestations are severe, you may see the underside of leaves littered with black dots.
Thrips feed by piercing their mouthparts into plant cells. This results in scarring that can be seen as stippling on leaves and irregular silver patches.
Another way to check for thrips is by checking for dry and distorted leaves. Leaves that have been damaged and had its sap sucked out by thrips will look mottled and almost papery in appearance, and might even fall out easily.
Last but not least, if you can see the thrips’ colonies of larvae that look like white, moving dots, you probably have an infestation on your hands.
In many cases, thrips are brought indoors through infested plants and plant cuttings. Additionally, they are often blown inside homes by strong winds, or are simply carried in through undisturbed clothing.
While thrips do have wings, they’re actually pretty weak fliers and are frequently just carried by strong winds. It’s not uncommon for thrips to be swept indoors by the wind, or by latching onto an unsuspecting person’s clothing.
But oftentimes, the most common reason behind why we find thrips inside our homes is simply because we’ve inadvertently brought them.
After purchasing plants with thrips from the nursery or using infected plant cuttings, it’s very easy for these insects to invade our other houseplants.
Ornamental houseplants like palms, monsteras and rhododendrons are all susceptible to attack. But some plants, such as the wandering jew, african violets, and weeping figs, all appear to be especially vulnerable.
In short, thrips seem to have very few limits, if any at all.
There are 7 measures that can be taken to prevent thrips from returning or entering homes. These measures would include:
- Avoid bringing thrips indoors
- Inspect plants often
- Remove debris
- Avoid excessive nitrogen
- Use traps
- Use row coverings
- Use reflective mulch
Dealing with thrips is tiring, and sometimes downright terrible for our plants. To make sure you don’t have to deal with this again, here are some of the things you should know to help prevent thrips from attacking your plants in the future!
The easiest way to prevent thrips from entering your home or garden is by making sure you do not bring them inside in the first place.
Speak with your local plant nurseries and make sure they have no infestations of thrips. Do this for everything containing organic matter that you may use, such as soil, plants, plant cuttings, and even compost.
You can inspect these items before purchase, and avoid anything that may indicate the presence of thrips.
As always, it’s important to keep an eye on what plants you do have. Regularly check up on your plants whenever you are watering, repotting, or just taking general care of them.
Make sure your plants are not touching each other to help prevent potential pests from spreading. Look for the signs of damage done by thrips, and keep an eye out for the actual pests themselves.
While you’re at it, I recommend removing any mulch or debris that may be left over on the top of the soil.
Thrips often overwinter protected underneath leaf debris. Their pupa typically finish developing in the soil or in mulch and come out fully grown into adults, so it’s best to remove anything that these insects can temporarily call home.
As useful nitrogen-rich fertilizers can be, it may be better to avoid using these in this situation. Regular applications of nitrogen-heavy fertilizer can encourage the growth of foliage in plants, which may attract more thrips to hide in the leaves and feed on it.
If you’re trying to avoid thrips, you don’t need to stop using your favorite fertilizer altogether, but you can try not to apply excessive amounts of nitrogen fertilizer.
These insects are weak fliers and highly attracted to the colors blue and yellow, especially western flower thrips. You can use this to your advantage and place blue and yellow sticky cards by your plants.
This can serve as a good way for you to monitor the presence of thrips, and start treatments as soon as you see any.
With row covers, you can easily shield your plants from thrips flying in, and laying eggs, protecting them altogether.
You can make your own in a pinch by slipping plastic bags over vulnerable plants, or purchase some good quality ones to ensure full protection. This may be the most effective method you can use.
Here is the row cover from Amazon that I recommend the most.
Reflective mulch works by reflecting light out and away from your plants to confuse flying insects, making it harder for them to properly locate your plants to lay eggs on.
This method has been proven to be quite useful in completely delaying or reducing the damage that plants may suffer. But these types of mulches are often fragile and not very cost-friendly.
Thrips are smaller and only grow to 1-2 mm, while fungus gnats can grow up to 3.17 mm. Also, fungus gnats look like fruit flies and feed off the roots of their host plants, while thrips feed off the leaves of plants.
Fungus gnats are different because their appearance is similar to fruit flies with more pronounced legs, and they are commonly seen in plants that are overwatered.
In comparison, thrips have long, slender bodies, and are not strong fliers, so they are usually only seen on leaves.
Moreover, fungus gnats are also 3.17 millimeters long, while thrips only grow up to 2 millimeters.
Thrips are entirely different insects from the larvae of fungus gnats that feed off the roots of plants, and you can tell if plants are infested by fungus gnats when you see their shiny and clear larvae inside the soil.
Can plants recover from thrips?
Plants infested with thrips can still be saved using the methods mentioned above, which involved physical removal, hosing, using predatory bugs, neem oil, castile soap, and rubbing alcohol.
But their chances of surviving may decrease the longer time goes on, and the worse the infestation becomes. It is crucial to start pest control as soon as these insects are seen.
Do thrips bite people?
If thrips are in environments where feeding is scarce, it’s not uncommon for them to possibly be attracted to the moisture of sweat on exposed human skin and bite them. These bites usually don’t result in serious consequences and are only mild irritations.
Are there any plants that repel thrips?
While some claim that growing certain plants can help repel thrips, there is no conclusive evidence for this. In fact, some of the plants that are commonly said to be thrips-repellent—like basil and chives—can still suffer from thrips attacks.
There are 6 different ways thrips can be eliminated. These management systems would include the use of physical control, biological control, hosing, neem oil, castile soap, and rubbing alcohol.
While chemical pesticides can be used, they are not recommended, especially for plants that are meant to be consumed or plants that are cultivated for their flowers.
- “Thrips: Pests of Ornamental Plants” by David Held and Jeremy Pickens in University of Alabama
- “Western Flower Thrips, Management and Tospoviruses” by Tina Smith in University of Massachusetts Amherst
- “Fungus Gnats” by J.A. Bethke and S. H. Dreistadt in University of California, Integrated Pest Management Program