Keeping houseplants can be a relaxing and rewarding pastime until it’s not. Finding pests on your prized plants can be stressful for you and your plant, but we are here to help with five tried and true methods to defeat pesky thrips on monstera to take your plant’s life back!
What are Thrips?
Thrips are small thin insects that are smaller than a quarter-inch in size. They feed on plants by creating small holes in the plant membranes and then drinking the plant’s sap. There are over 6000 species of thrips and not all of them are pests, but the ones most commonly found on houseplants are.
Thrips are most commonly yellowish, dark brown, or black and they can cause significant damage to houseplants in a very short period of time.
The lifecycle of thrips allows them to infest plants rather quickly. The preferred temperatures for thrips and the ones they reproduce the best in are 80-85 degrees, but they can survive in temperatures as low as 50 and as high as 90 degrees.
When in their ideal temperature range, thrips can complete their metamorphosis from egg to adult in just 14 days, in cooler temperatures it can take up to 40. Thrips usually hatch from eggs on the leaves of your Monstera plant. Here they feed on the monstera’s sap and will go through 3 nymph stages, at which point they fall down into the soil to complete their transformation into adults.
Adult thrips then climb back up the plant, breed, and lay eggs near new holes in the leaves. Adult thrips can live up to 45 days and produce 15 sets of eggs before passing. As you can imagine, this lifecycle and prolific breeding pattern can create an overwhelming infestation in a very short period of time.
Symptoms of Thrips
I always recommend spending time with your plants weekly and giving each one a once over to make sure they are free from pests and looking healthy. If you do this, you may be able to catch thrips on your plants before there are any signs or symptoms of an infestation.
If you do see thrips or other insects on your plant, be sure to immediately isolate it from the rest of your collection. This will stop them from spreading to the rest of your plants. If you are lucky enough to have caught them early, skip ahead to the treatment methods below. Otherwise, here are some symptoms you may have noticed on your plant.
Thrips feed on the sap of monstera plants, which can cause the plant to have difficulty staying hydrated. A leaf that isn’t receiving enough nutrients and water can begin to turn yellow.
Black spots on the bottom of leaves
If you look at the underside of the leaves on your monstera plant you may notice little black spots. This is excrement or poop from the thrips. While this doesn’t hurt the plants, it is a sign of an infestation.
When your monstera is being fed on by thrips, it will usually start looking lackluster or sad. Wilted leaves, curling leaves, and overall dehydration are all symptoms of thrips and mean your plant is in need of help.
There are quite a few methods for treating thrips and each has its pros and cons. We have them outlined here.
The most effective way to get rid of thrips is by introducing ladybugs. Ladybugs can usually be purchased online and shipped to your door. While we may think of them as cute, harmless insects, they are actually voracious predators that will kill and eat aphids, thrips, and other small pests.
While ladybugs are definitely the easiest option, there are drawbacks to using them. Most ladybugs that are shipped out are non-native species, which means they aren’t safe to release outside and they are frequently species that can bite. If you are ok with these downsides, ladybugs may be the best way to go.
Place your plant outside
If you like the ladybug idea, but don’t want to release hundreds of ladybugs in your house, there is another option. If the weather outside your house is about 60, you can place your monstera plant outside in partial sun and allow nature to take its course on your thrip infestation.
There are lots of bugs, lizards, and birds that love to feed on thrips, so by putting your plant outside you are feeding nature and getting rid of the pesky critters that are harming your plant.
This option is only viable in the spring, summer, and fall when the weather is right. Placing your plant outside in cold weather will cause it to go into shock and it will die. Also, avoid placing your plant in direct sunlight as it will likely burn.
Thrips are attracted to the colors blue, yellow, and white. This means that you can use sticky traps of these colors to attract and catch thrips on your monstera. Simply put traps on the soil of your plant and hanging near your plant and they will soon fill up the paper. This method can be a slow one, so it’s best employed in conjunction with other methods, but not safe to use while releasing ladybugs.
Insect traps are available for sale in most home and garden stores, but if you want a safe DIY option, you can take thick paper such as a post-it note or an index card. Cover the card in Vaseline or honey and voila, you have sticky traps.
Using a lint roller directly on your plant works similarly to sticky traps and is a great way to kick off whichever treatment method you choose. As you swipe the roller on the leaves and stems of your plant thrips will be caught on the paper. Once the paper seems semi-full, you can rip the sheet off and deposit it in your outside trash bin. Continue until you are no longer picking up any thrips.
There are two options for insecticidal soap. You can purchase a ready-made version at your nearest home and garden store such as Lowes or Home Depot, or you can DIY your own version. Before using either, you will want to make sure to water your plant so it doesn’t absorb much of the soapy water into its soil and to its roots.
When I need to treat insects on my plants, I prefer to DIY my own soap. It’s cheaper, better for the environment, and safer for myself and my pets. To make your own soap you will need a gallon jug, dish soap, and a spray bottle.
Fill the jug full of lukewarm tap water, add in 4-5 tablespoons of soap, and shake to mix. You will want to use the mixture as soon as you have mixed it, so pour it into a spray bottle and liberally coat your plant. Repeat every day to every other day for the best results.
While I have never tried this method, I know some friends have taken smaller plants and dunked them upside down in the soap mixture. They have observed good results with this method, but it can overwhelm your plant.
If you prefer to just use store-bought soap, you can. Do a test run on just one leaf to make sure the soap isn’t too strong for your plant. If you notice burns the next day, you will need to dilute it down to half strength, otherwise, you can apply it all over your plant including the underside of the leaves.
Battling a pest infestation can be hard on you and hard on your plants. It’s likely that your monstera plant will need some babying after the experience. To help your plant to recover, you will want to trim away any leaves that are damaged, yellowed, or brown.
These leaves likely won’t recover and while they are attached your plant will be sending energy to them that is basically being wasted. Removing these damaged leaves will allow your plant to focus on healthy new growth and repairing the damage it may have sustained to its roots and main stem.
While it can be stressful, repotting could also be a good option after you have removed the thrips from your monstera. It could even be necessary if you used insecticidal soaps. Lingering soap could cause damage to the roots of your plant, so better safe than sorry and repot.
If you weren’t able to save your plant, you may be able to make new ones. Monstera tend to be very easy to propagate, and if your plant sustained a lot of damage from thrips it may be best to just start over.
To create cuttings, you will want to choose leaves with the least damage and cut them just below the node on the parent plant. You then have two options.
You can let the cuts heal over, dip them in root hormone, and place them in soil to grow new roots. This method seems to be a little slower but can work well and is a bit lower maintenance.
You can also place them directly in clean water. If you choose the water propagation method, which is admittedly my favorite, you will need to change the water roughly once a week. I usually use fish tank water for my propagation, since I also have several fish tanks and the water has nutrients in it that seem to help the plants grow.
If you don’t keep fish, no worries, regular tap water can work fine too. When you start to see roots growing, you will want to transfer your new plants into wet soil. Slowly transition the plants from wet soil to your normal water routine over a couple of weeks and you are set!
How to prevent thrips from attacking your Monstera
Prevention is key to the healthiest plants and preventing thrips and other pests is much less stressful than having to treat an infestation.
Before buying plants and bringing them home, you should always give them a once-over and check for signs of insect infestation. Brown or yellow leaves, wilting leaves, and brown spots can all be indicators of an unhealthy plant. Many people like to “rescue” sick plants when they see them, but this is definitely a risky move and could lead to an infestation of pests in your other houseplants.
Always quarantine new plants you bring into your house. Plant stores do their best to prevent pests in their stores, but you just never know if a new plant has hitchhikers, so quarantine is the first line of defense for your beloved plants.
Start a weekly healthy plant checkup routine. Walk around your plant, give everyone a once over, look at and clean leaves. Spending time with your plants can lower stress levels and keep you healthier, so plant checkups are actually good for you and for your plants!
Some plant keepers also use neem oil as a preventative measure to keep their plants safe from pests. If you want to try this method, it is rather simple. Just buy a ready-to-use neem oil mix and spray it on your plants once a week in the morning or the evening. Neem oil does have a very strong scent and is not safe to use around rodents or birds, so keep this in mind if you have small pets in the house.
The last line of defense against pests is a healthy plant. Most pests will attack unhealthy or stressed plants before they will healthy ones. Having a regular watering schedule, keeping your plant fertilized, and making sure it is getting enough sunlight is the best way to keep your plant healthy and keep thrips from attacking.