Thrips are one of the worst indoor house plant pests you can encounter. These pests are stubborn and they can make your plant very sick.
Sick to the point of serious concern. You should feel concerned about a thrip infestation, big or small.
Some species of thrips even bite humans.
They carry a few diseases and viruses that cause severe harm, if not permanent damage to your plant.
It takes little effort on the thrip’s part. They feed off of an infected plant then head over to your plant to feed. Now, they’ve infected your plant.
It’s all in the saliva. Scary, right?
You won’t always know right away if your plant is being attacked by thrips. They’re sneaky and they like to hide. They also don’t get very big.
That’s why we’re always preaching prevention. But we know you can’t always stop an infestation of any type of bug. Sometimes they just happen.
But despite how scary thrips seem, you can get rid of them if you stay persistent.
We’re going to share our secrets with you on how to prevent and get rid of thrips. So, keep reading if you want to know everything we know.
What are Thrips?
Thrips belong to the order Thysanoptera family. And there are more than 6,000 species of thrips.
Over 400 of those species live in North America.
Most thrips only grow to be about 1/25th of an inch (or 1 millimeter) in length or less. They have fringed wings and thin cigar-shaped bodies.
Thrips come in several different colors. It all depends on the thrip species.
From your perspective, thrips will resemble small threads. That’s only if you have decent vision. They are even harder to see for others.
Thrips can fly but since their wings are feathery, they don’t get very far. They fly in an unsteady circular motion. They rely on the wind to help them fly from one place to another.
It’s believed that some thrip species pollinate plants. Other bugs won’t pollinate the same plant they feed off of. This is a behavior unique to these bugs.
A thrip’s favorite plants are veggie plants and flowers.
How Thrips Reproduce
Some thrips are asexual. They don’t need a male thrip to reproduce. The female thrips do all the work on their own.
This process is parthenogenesis.
Others are sexual. The male thrips compete with other males. The winner gets the chance to mate with the female thrips.
Once spring hits, female thrips produce around 80 eggs. Some species lay these eggs inside the tissue of a plant through a slit they create.
Other species lay their eggs on the leaves and buds of a plant.
How long it takes for the eggs to hatch depends on the weather and temperature.
Hotter weather means the eggs hatch in about three days. Colder weather means it takes about two weeks.
When the eggs hatch, larvae emerge. The larvae suck on the sap out of the plant to survive.
The larvae move to the potting soil of the plant. This means they’re ready to change into pupae. This is their last stage before they become adults.
While they’re pupae, they develop buds where their wings go. They also develop genitalia that determines their sex.
After this stage, they gain their wings and become adult thrips. They live between 30 and 45 days.
Female thrips can produce anywhere from eight to 15 generations a year.
How Thrips Attack Your Plant
Like many indoor plant pests, thrips feed by penetrating a plant. They suck the pollen out with their sharp mouths.
When they penetrate the outer layer of a plant, they introduce their toxic saliva. The toxins in their saliva rupture the plant’s cells.
These ruptured cells make the plant sick and cause the main symptoms you see in a thrip infestation.
They feed in large clusters. It’s rare for thrips to feed alone. All these bugs feeding off one plant does horrible damage.
Thrips also like to chew on the flowers, fruits, or leaves of your plants.
The worst part of an infestation involves the viruses they bring, by feeding on your plant.
One virus happens to be the tomato spotted wilt virus (or the tospoviruses). Despite the name, tomatoes aren’t the only plants affected by it.
The tomato spotted wilt virus affects 35 different plant families.
This awful plant virus has six strains. And thrips are responsible for a large amount of its’ transmission.
When a plant has the tomato spotted wilt virus, leaves might cup or curl. The cupped leaves face down. The younger leaves on your plant will bronze.
The leaves droop enough that it makes your plant look wilted. They might even start dropping off the plant.
Weird circular spots will cover the fruit on your fruit plant. There might be bumps on them too.
Another scary virus transmitted by thrips is impatiens necrotic spot virus. This virus causes all kinds of awful symptoms for your poor plant.
The biggest symptom is the sunken spots on your plant’s leaves. These spots are usually black, brown, or white. They’re called necrotic spots.
The leaves turn yellow and wilt. As the virus keeps progressing, the leaves will drop off the plant.
The growth of your plant will either move slowly or stop altogether. Flowering will produce deformed flowers. Or the plant won’t flower at all.
Of course, impatiens necrotic spot virus can lead to death if it’s not treated right away.
How to Prevent Thrips
Preventing thrips is much easier than treating a plant for them. Like with all plant pests, there are preventative steps you can take.
The easiest way to prevent thrips is to check every plant you’re considering buying. Double-check any plant for pests before you bring it into your home.
If you suspect your new plant has an infestation of thrips, place it in a separate room for at least two weeks. Treat the plant right away.
Never bring in debris or sticks inside your home without inspecting them first. Remember, they’re teeny tiny bugs.
There could be thrips living in your backyard without your knowledge.
Check your plants almost every day. You’ll be able to weed out a problem before it spreads.
Make sure you’re not over-watering your plant. Besides all the other issues that come along with over-watering, it stresses it out.
Plants are more vulnerable to all types of pests when they’re stressed.
Kaolin clay (also known as China clay) is a great way to protect your plant from these bugs. This clay has its’ nickname because it’s the main ingredient used to make fine china.
You can buy kaolin clay from retailers that sell other types of art clay.
The kaolin clay mixed with a few other ingredients will keep the bugs at bay. Most insects won’t pass a line of the stuff, including thrips.
To make a kaolin clay recipe you need:
- 1 tablespoon of pure liquid soap (you can substitute with mild dish detergent)
- 1 quart of kaolin clay
- 3 quarts of water
- Spray bottle
In a big bowl, mix the clay and water. Once that’s mixed, stir in the pure liquid soap. Pour the kaolin clay soap into an empty and clean spray bottle.
Spray the mix on the entire plant. This will keep the thrips away from it. Make sure you do this once a week if you have a reason to worry.
How to Get Rid of Thrips
When you’re concerned that thrips have infested your plant, you need to do your due diligence to find out for sure.
First, check if you can see the thrips themselves. Keep in mind that they feast in clusters. This should make it easier to see them.
If they’re feeding on a leaf and you move it, the thrips are going to fly around. Some thrips might even jump.
As thrips feed on your plant, several symptoms will jump out at you.
The leaves turn pale. They might have silver splotches all over them. When the infestation is large and the thrips keep feeding, the leaves will drop off your plant.
The body or stem of the plant will show major signs as well. The stem will be discolored. It will twist and they can become scarred from the scratching of the thrips.
The symptoms get worse if thrips transmit a virus to your plant.
Symptoms will include yellow or wilting leaves. They might have sunken spots all over them.
Anything strange and unusual can be a big sign that your plant is suffering from a bad virus.
Another symptom are galls on the leaves of your plant. They leave galls behind in their different feeding spots because of irritation.
Galls are abnormal growths on the leaves of a plant. They also occur on flowers.
Once they start to grow, galls are super hard to miss. Even when you’re not trying to check your plant.
Small Thrip Infestations
Even small thrip infestations can be difficult to treat. They live in large groups and reproduce fast.
If you’ve caught a thrip infestation early enough, there’s a simple way to get rid of them.
Shake the branches of your plant. You need to shake them hard enough to knock the thrips off. You don’t want to get too rough with your plant either.
Make sure you place paper towels on the potting soil so they catch the thrips. It makes it a whole lot easier to see them this way.
You want to remove all the insects you shook off as soon as possible. Otherwise, they’re going to fly right back up on your plant.
Prune any infested areas of your plant. While you’re at it, prune any areas that are damaged from thrips or a virus.
Use a pair of shears that you dipped in 70% isopropyl alcohol.
You can try spraying your plant down if it’s strong enough to handle it. Use a hose with a high-pressure nozzle. This will send the thrips out of your plant, flying.
Don’t forget to spray underneath leaves of the plant.
One method to get rid of the adult thrips is to use blue or yellow sticky traps. You need to place the sticky traps around the potting soil.
The thrips will land on the traps when they go to land on the plant’s soil.
Change the traps out the next day and throw them away as soon as possible. Place new sticky traps down every few days.
When the thrips start to dwindle, switch to changing them once a week.
Try spot treating your plant with 70% isopropyl alcohol. But before you do, test the alcohol on a small area of your plant to make sure it doesn’t harm it.
If it’s too strong, try diluting the alcohol with water.
Now, take a cotton swab or cotton ball and cover it in the alcohol. Start dabbing all the infested areas. Don’t forget to check under the leaves too.
Neem oil is the best choice to rid your plant of a small thrip infestation and to stop them from spreading. Neem oil is also your weapon of choice if your dealign with other annoying plant pests such as aphids, fungus gnats or mealybugs.
So, when you have a chance to pick up some neem oil you should. You’ll understand the many benefits later on.
Take this neem oil and spray down your plant with it. Make sure it’s covered all over with the oil, including under the leaves.
Don’t forget the spaces where the branches and the leaves meet.
Since thrips are easy to disturb, spray any flying bugs as they pop up. The neem oil covers the pores of the thrips, suffocating them.
If the infestation is super small, you can use the neem oil to spot treat your plant instead.
Large Thrip Infestations
You’re going to get frustrated trying to get rid of a large thrip infestation.
But if you want to save your plant, you can’t give up. We do have a few methods that might help.
You will have to repeat these methods several times to finally rid your plant of the pests.
We always urge you to try insecticidal soap for any large pest infestation. It’s a reliable and natural pesticide that almost always has good results.
The fatty acids in the soap are perfect for killing soft-bodied bugs. These fatty acids are strong enough to dissolve the membrane that surrounds thrips.
When the membrane dissolves, the thrips lose a large amount of moisture. This leads to their death.
We have a special insecticidal soap recipe that will not only kill most the thrips but drive the rest away.
- 1 tablespoon of mild dish detergent
- 2 tablespoons of light vegetable oil (you can substitute with olive oil)
- 1 teaspoon of garlic
- 1 quart of water
- Spray bottle
First, mix the light vegetable oil and water in an empty and clean spray bottle. The vegetable oil is going to make the soap mix stick longer to your plant.
Then add the garlic and mild dish detergent. The vegetable oil and dish detergent make the soap thick so you’ll need a utensil to mix it all.
Before you apply the soap, test a small area of your plant. Wait a day and see how your plant reacts to it.
Now that you have your insecticidal soap ready, it’s time to put it to good use. All you have to do is spray down your plant.
Concentrate on the areas that you know there are clusters. Check under the leaves, it’s the favorite spot of most thrip species.
If you wait until early morning or at night to spray, the insecticidal soap will stick even longer.
You need to do this a few times a week for at least three weeks.
When the going gets tough, try out diatomaceous earth. Diatomaceous earth is microscopic and fossilized aquatic organisms in dust form.
These organisms are known as diatoms.
So, why do people use diatomaceous earth on plants? Well, diatoms have silica in them.
Silica removes the waxy protective coating from insects. That waxy coating preserves moisture.
When the coating disappears, the thrips lose all that moisture. They become dehydrated and die right away.
You’re going to need a face mask and eye protection. Diatomaceous earth is dust. If you’re not protected there’s a strong chance you’ll end up with it in your lungs or your eyes.
To use the diatomaceous earth, powder it around the base of your plant. This stops any new thrips from coming in.
Don’t forget to dust the infested leaves. If you’re not sure where the clusters are, it’s safe to dust the whole plant.
To make sure you’re getting every single thrip, you need to repeat this process. Repeat it every other day until you’re sure your problem is gone.
If you have no luck and decide to turn to chemical pesticides, make sure you choose one that’s made for indoors.
Test an area of your plant to make sure it’s okay. The chemicals aren’t the best for any plant.
Why isn’t the diatomaceous earth killing any of the thrips?
If the diatomaceous earth isn’t helping at all, you might have the wrong kind. You want diatomaceous earth that’s labeled as food-grade. The diatomaceous earth made for pool filters won’t do anything to bugs.
Can thrip bites make you sick?
Thrip bites can’t make you sick unless you have an allergy, which isn’t common. People sensitive to bug bites, one of these bugs could make the area bitten break out in a rash.
Why isn’t chemical pesticides taking care of the thrips?
One of the biggest reasons thrips are hard to get rid of is because they develop an immunity to chemicals. Your pesticide may have worked the first time but it’s not going to keep killing them.
Thrips are the bad bugs in the houseplant world. They tear up your plant and suck the life out of it. Worst of all, they pass awful diseases from one plant to another.
The best method for getting rid of thrips is dusting your plant with diatomaceous earth. When you find yourself frustrated, give it a try.