Thrips On Monstera: Causes, Identification & Treatment


Finding thrips on houseplants is one of the biggest pains in the life of a gardener. Thrips find their way back inside homes through cut vegetables and flowers from the garden. It takes 1 to 2 weeks for an egg to become an adult. If you notice tiny black bugs on Monstera, it is probably under thrip attack. These are water-loving pests that thrive under warm and dry conditions.

Thrips on monstera cause discoloration and distortion of the leaves. Isolate the affected plant and treat the infestation using organic treatments such as neem oil, sticky traps, and attracting beneficial pollinators such as ladybugs. The ultimate chemical solutions include insecticidal soaps and oils such as Dead Bug Brew and systemic granules. 

How To Identify Thrips On Monstera

If out of nowhere you notice discoloration of the foliage, wilting and drooping leaves, there might be a pest infestation. Check the undersides of the leaves using a magnifying glass and look for these tiny pests. Thrips reproduce fast and in no time can cause the leaves to look distorted and pale.

To identify thrips infestation on Monstera, look at the plant closely. Have a nice look at the leaves and stems using a magnifying glass. There could be white, brown, or black marks on the plant.

What Do Thrips Look Like?

Thrips are tiny, rice-like, soft-bodied pests that suck the sap out of the leaves and stems of the plant. The adults are about a quarter of an inch and have two pairs of wings. Baby thrips are wingless and are much more difficult to spot with the naked eye. Without a magnifying glass, the adults look like tiny threads or worms and fly away when disturbed.

The adults live for up to one month but they reproduce quickly. It takes as little as two weeks for thrips to complete their life cycle from egg to adult. There are 12 to 15 thrip generations per year from an egg to an adult fly.

In spring, females insert their eggs in leaves and stems. Each female produces up to 80 eggs that hatch within days in warm temperatures. The eggs become wingless larvae that feed on the sap. You can find eggs laid on tender leaves on sides facing the stem. The eggs turn yellow as they mature.

Where Do They Come From?

Thrips are quite common among the pests found on houseplants. Most often, they find their way inside through cut vegetables and flowers that you bring from the garden. They can also come inside through newly bought plants from stores. When the plant is kept outdoors in summer and brought inside in the winter months, thrips find their way inside.

The adult thrips do not lay eggs in the soil but on the plant itself. Some larvae (nymphs) fall in the soil. Once the nymphs mature, they fly back to the plant leaves and stems. The worst part is that they are not noticeable until the population grows quite large.

5 Signs And Symptoms Of Thrips Presence

Thrips can reproduce asexually. So it takes very little time for a few thrips to become hundreds. You must keep a regular check on the plant and check for thrips presence. Let us have a look at some signs and symptoms that you might see.

Yellowing and Browning of Foliage

While there could be many reasons behind the yellowing of foliage, you should keep an eye out for pest infestations. Thoroughly examine the plant to determine the exact cause of yellowing. Yellowing starts at the bottom of the leaves.

The first sign of a thrip infestation is the presence of yellow or brown patches on the undersides of the leaves. If left untreated, the patches become darker with time. Thrips also leave discolored spots around the leaf veins.

Wilting and Curling Leaves

A thrip infestation can suddenly cause the leaves to curl and wilt. Drooping leaves could also be due to underwatering. But determine the exact cause by looking at the leaves. The leaves look limp and lifeless if there is a heavy infestation.

Black Spots of Thrips Excrement on the Leaves

Tiny black spots on the foliage are most often, nothing but thrip poop. Check for these black spots on the undersides of the foliage. If you notice tiny, light brown thread-like worms on them, the plant is infected by thrips.

Distortion of New Leaves

Thrips cause the new foliage to grow distorted with tiny holes in Monstera leaves growing larger over time. Sometimes, the leaves would not even open because of a thrips attack. Thrips-infested plants produce deformed main stem leaves. The new leaves are often circular in shape.

Silvery Streaks on Older Leaves

Sometimes, silver speckles appear on the undersides of the older leaves. Thrips suck the sap out of the tissues of these older leaves. You might also find some thrips larvae in soil. These nymphs fall into the soil when an adult female lays eggs on the leaves and stems.

How To Get Rid Of Thrips on Monstera

Among all Monstera pests, thrips cause the most damage and are also hard to get rid of. The sooner you spot them, the easier it will be to control their spread. We will explain in detail some techniques to get rid of these annoying pests.

Using Lint Rollers

This method works well when the spread is not much. If you notice a few thrips on one or two leaves, you can remove them by watering the affected part. If the infestation is less, removing them by a lint roller works quite well. Glide the roller on the affected leaf and the thrips will stick to the adhesive.

Yellow or Blue Sticky Traps

Thrips are naturally attracted to colors such as blue, white, and yellow. Place a trap in your planter and wait for thrips to get attracted to it. You can make a sticky trap at home using white or blue paper and by applying glue or vaseline to it.

Systemic Insecticide for Thrips

Systemic insecticides or horticultural soaps such as imidacloprid are effective in getting rid of thrips that burrow inside the plant tissue. It does not require repeated uses if the infestation has not spread on a large scale. Insecticidal soaps help in breaking down the bug’s outer shell, making them dehydrated.

Spray a small amount of soap on the affected leaves and stems. Check again after 24 hours for brown spots. Repeat this process for at least two weeks and you will see a significant reduction in thrips. Spray the soap in the evening to prevent it from drying out fast. Once the soap dries, it would not have any effect on thrips.

You can make a homemade insecticidal soap by adding in 4 to 5 spoons of soap in a gallon of water. Mix it all and spray regularly until you see improvement in the plant’s health.

Releasing Natural Predators

Beneficial insects such as ladybugs are an eco-friendly way of getting rid of thrips. They feed on both the eggs and larvae before they become adults. They also feed on the thrips in soil. You can purchase lady beetles from retail nurseries and garden centers. Keep the ladybugs refrigerated before releasing them. If they are left at room temperatures for longer periods, they will deteriorate.

Pruning the Distorted Leaves

Always prune the damaged leaves before thrips spread to other parts of the plant. Pruning also helps the plant focus its energy on producing new growth from where the cut was made. Do not prune the leaves while the plant is inside the house. Take it outside and cut off all the damaged leaves.

Thrip Damage Control

Once your Monstera is infested with thrips, it may be hard to get rid of them. But it is not entirely impossible. Let us look at some techniques that you can follow to reverse the damage already done by thrips on your Swiss Cheese plant.

Recovery in the Least Damage

Detect the problem as early as possible. If the thrips have not caused much damage, the plant can recover easily in a few days’ time. Provide the plant with optimum growing conditions and take all preventive measures to avoid a thrip infestation.

Submerging the plant in water for one or two days helps in mild infestations. Drag a wet cloth on the affected leaves of your Monstera. Giving the plant a good dip in water helps in cleaning the leaves and removing the dirt and pests.

Recovery in case of Medium Damage

Cut off the infected parts of the plant and take new stem cuttings to propagate. Take the cuttings from the healthy part of the plant that is free from thrips. Even if you lose the older plant to thrips, you will have a new one ready.

If nothing seems to work out, use insecticidal spray for thrips such as Emamectin benzoate, Imidacloprid, Fipronil, and Dimethoate. Spray the insecticides thoroughly on leaves and soil. Repeat this process until there is a significant decrease in the pest population.

Recovery in Full Damage

If the plant looks lifeless and almost all the leaves are either discolored or wilted, it is not possible to save it. Discard it and save other houseplants from the infestation. Strong insecticides fail to work in severe infestations since the plant becomes incapable of survival.

Keep Your Houseplant Safe From Future Infestation

It is always better to prevent the problem before it causes any damage. Keep your Montera safe from future infestation by following some preventive measures.

Regularly Removing Weeds From the Soil

Apart from taking up the nutrients of the plant, weeds offer food and shelter to unwanted pests like thrips. It makes a good hiding place for thrips. Remove the weeds from the soil as you see them. It will make it easier for your spot thrips on the soil surface.

Cleaning the Foliage

Pests like thrips and spider mites are easily attracted to dirty leaves. Maintain cleanliness and clean your Monstera once a week with a damp cloth. Use the damp cloth to wipe off dirt, dust, or other particles from the leaves. You can also rub a cloth dipped in alcohol over the leaves to prevent pests.

Isolating the New Plants

Always make it a habit to isolate newly bought plants from other houseplants. Sometimes, store-bought plants carry pests and they can infect other existing plants, if unnoticed. Keep the plant isolated for a few days and check its leaves for any pests.

Using Pest Repellent Plants

Plants like basil and rue invite beneficial pollinators and insects and repel pests. The oil in basil repels thrips and other harmful pests. Place your Monstera near such plants to protect it from pests. Thrips cannot tolerate the strong smell of these plants.

Applying Neem Oil

Neem oil works as a great organic pesticide. To use Neem oil for thrips, mix 4 to 6 spoons of the oil in a gallon of water. Spray it generously on the leaves and its undersides once a week. Use it in the early morning or evening as thrips are the most active in the morning and evening hours. It lasts for up to two days on the plant. Avoid overusing Neem oil as it can cause root burn, if applied directly to the soil and may eventually kill the plant.

Helpful Predators

Some natural enemies of thrips include predatory mites, minute pirate bugs, lacewing larvae, and lady beetles. They feed on thrip eggs, larvae, and adults. Most of them are commercially available in garden centers and nurseries. First, spray the plant with water and then release the insects to attack all harmful pests.

To End

Monstera plant bugs such as thrips are a nightmare. But if you know how to care for the plant and take preventive measures to protect it, your Monstera will be happy and healthy. For severe infestations, use insecticidal soaps and systemic granules. Check your plant regularly and apply Neem oil to keep these pests at bay.

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