How to Get Rid of Indoor Plant Pests

Plants have been on earth for a very long time and in that time they have grown alongside insects and arachnids. Over time, various arthropods have evolved to feed on the sugars plants produce during photosynthesis. Indoor plants are, unfortunately, prime targets for these insects. Luckily, there are several approaches you can take to keep your plants pest free.

Before we dive into methods to control and rid plants of pests, it’s important to become familiar with the most common plant pests. There are several common plant pests you’re likely to encounter, these are ‘the usual suspects’ when it comes to plant pest. While they vary in size and morphology, all of them are bad news for your leafy family members! 

Common Indoor Plant Pests

In order to combat pests on your indoor plants, you first have to know what pests you’re dealing with. Some insects and arachnids are actually, despite what many people think, harmless or even beneficial to your plants! Let’s look at a few of the ‘usual suspects’ that are known to be bad for plants and cause plant damage.

Indoor Plant Pests: Aphids

Aphids are very common plant pests. Generally, aphids tend to bother outdoor plants more than indoor; however, certain plants attract aphids more than others. These plants will draw aphids inside. Ferns and some succulents are common targets for aphids as are ‘vegetable’ plants such as peppers and broccoli.

Annoyingly, an aphid infestation can go unnoticed for long enough for it to become a serious problem. Plants that are dense and bushy make identifying an aphid infestation particularly challenging. These tiny insects can fit into the tiniest of leaf folds and can even be found in new leaf primordia (newly forming leaves or ‘buds’). 

Aphids primarily come in three different colors: green, black, and orange. Regardless of color, all three of these aphid varieties have the same effect on plants. These small insects have piercing mouthparts that penetrate plant tissues in order to suck the sugar-filled liquids out of plants’s tissues.

Signs of Aphid Presence

Due to their small size - adult aphids range from 2 - 4 mm (1/16 - 1/8 in) - aphids can be tricky to spot on plants. The color of the aphid will either make identification easier or harder. Black aphids are easiest to identify as they contrast well against green foliage. Green aphids can be incredibly hard to notice on certain plants. Luckily, there are a couple reliable signs of an aphid infestation.

Drooping and or yellowing leaves, stunted growth, and leaf abscission (dropping leaves) are all signs of a severe aphid infestation; however, they are also signs of several other issues and are not a surefire sign of aphids. Instead, look for little white flecks on the plant’s foliage - these are the molts of aphids as they’ve matured. Luckily, aphids have another unique telltale sign you can watch out for.

Aphids, as a byproduct of their feeding, produce a substance known as honeydew. Honeydew is a sugar-rich sticky fluid that is almost semisolid. Honeydew is a food source of ants! Ants actually “farm” honeydew from aphids by moving the aphids around to find new vessels to tap. The aphid gets a new meal and so do the ants. If you suddenly notice ants running along your plant’s leaves and stems, chances are you either have aphids, or the next culprit on the list.

Indoor Plant Pests: Scale and Mealybugs

Scale and mealybugs are insects that form a sort of hard covering over their bodies to protect themselves while they use their piercing mouthparts to suck fluids out of plants. Scale come in a variety of sizes and appearances, from orangish-brown to pure white, scale look like small oval shaped scabs and usually appear on a plant’s petioles (the stalk that connects the leaf to the stem) or on its leaves, usually at the basal end (where the leaf attaches to the petiole). 

Infestations of scale can range from a few individual insects to several thousand on one plant. In severe cases, an infestation may be so bad that the scale completely cover parts of the plant  - all you can see is scale! Usually, scale are not capable of causing severe harm to the plant they are feeding on, however, if the infestation is severe enough or they are never dealt with, they can cause significant damage or even death.

Signs of Scale and Mealybug Presence

Scale can be incredibly difficult to notice on plants and can often go unnoticed for quite some time. Aside from the white variety (Cottony Cushion Scale), scale are often a very similar color to the surface they are feeding from. Due to their small size and lack of quick movement, scale can blend in very well on certain plants. 

As with most plant pests, signs of decline in the health of your plant can be an indicator of scale. Unfortunately, due to these signs also being signs of several other issues, they are not reliable to identify if you have scale (unless you have a severe infestation!). Generally, signs of overall plant decline such as dropping leaves, yellowing leaves, or wilting leaves (incipient plasmolysis) are signs you need to inspect the plant to find the root cause of the decline.  

Luckily, like we discussed with aphids above, scale also have a symbiotic relationship with ants. In general, common household ants don’t spend much time running along plants unless there is a good reason to - namely, a food source. If you suddenly notice ants on your plants, there is a good chance you’ve been visited by some indoor plant pests!

Indoor Plant Pests: Spider Mites

Spider mites are one of the worst indoor plant pests to deal with. These little arachnids (that’s right, these little arthropods are arachnids, not insects) are even smaller than aphids and their populations can explode very quickly. While you can spot spider mites by visually inspecting your plants, their minute size (they can be as small or smaller than a period in a sentence) mean that a magnifier of some sort will make the job much easier. 

There are several different types of spider mites but one of the most common is known as the two spot spider mite. These little arachnids have two colored spots on their abdomen. Identification is easiest with magnification, though the largest adult mites can be identifiable if you happen to have excellent vision.

Signs of Spider Mite Presence

All mites are broadly similar in body shape and, as a result, are not overly easy to tell apart. Spider mites are an exception (luck happens to be on the plant parent side here!). These mites are named spider mites because, like spiders, they make webs when they take up residence on one of your beloved houseplants. The webs are very fine and not overly apparent unless you get in close, though they do offer an easier to see indicator of spider mite presence than the eggs or juvenile mites do!

Things to watch out for when you think you’re plants may be dealing with spider mites are webbing on plant foliage and leaf curling. Oftentimes the leaf edges of plants infested with spider mites will begin to curl toward each other and webs will likely be present connecting to two curled edges. If you suspect spider mites may be attacking your plants, carefully inspect each leaf (especially new growth) for signs of spider mite presence.

Indoor Plant Pest: Thrips

Thrips are another common plant pest that can be tricky to spot before you have a full-blown infestation. Thrips are long and slender insects which make them easier to correctly identify compared to spider mites or scale. Thrips will most commonly appear on the underside of your plant’s leaves. Male thrips do have wings and are capable of migrating easily between plants which can complicate controlling them.

Thrips are quite small and can come in a variety of colors. Female thrips lay their eggs inside of plant tissues other than on the surface of foliage, stems, or soil. This makes controlling populations of thrips more complicated than scale or aphids.

Signs of Thrips Presence

Identifying thrips on your plants is not easy due to their small size, identifying their eggs in almost impossible. All of the usual signs of plant decline can be present due to thrips but the adults can be identified easiest by shining a flashlight under the leaves of your plant as you insect the leaf. Since thrips look like little dark lines, inspecting any unusual shapes you find on the leaves is best practice. 

Another helpful way to identify thrips is to take a blank piece of white paper, set it under your plant, and tap the leaves over the paper. The tapping will dislodge some thrips causing them to fall onto the paper where it will be much easier to confirm if they are present on your plant.

Control Methods to Get Rid of Indoor Plant Pests

Now that we’ve covered a bit about the common indoor plant pests and what to look for to identify them, let’s get to the good stuff, controlling them and protecting your plants! In general, there are two main methods for ridding plant pests from your indoor plants, chemical control and physical control. Both methods have benefits and drawbacks so let’s look at both to see which sounds best for you.

As a note, at the Ethical Botanist, we believe in using and promoting products that are as non-harmful to people, plants, and animals as possible. While these control methods are, obviously, harmful to indoor plant pests, they are less harmful to everything else than, say, commercial pesticides.

Chemical Control Methods for Indoor Plant Pests

In terms of pest control methods, chemical methods are among the most effective at ridding your plants of pests and controlling the reappearance of said pests. Our two favorite chemical control methods are Cold-Pressed Neem Oil and SNS 209.

Indoor Plant Pest Control: Neem Oil

Neem oil is one of the most common plant pest control products available; however, not all neem is made equally. Neem oil comes from pressing the seeds and fruits of the Neem tree (Azadirachta indica). The pure neem is then mixed with an emulsifier (a substance that reduces the hydrophobicity of the oil and allows it to mix with water) to create a spray solution. You can usually buy pre-made neem spray solution or make your own. 

Getting a pre-made neem solution is definitely the easiest option; however, there can be drawbacks to this. Pre-made solutions often use less pure neem oil or even other products of the process that have very little neem oil in them. This makes it cheaper for the company and less effective for you. Additionally, many pre-made solutions use emulsifiers that are unlabeled or are simply listed as “Inert Ingredients”. One has to wonder, if they are using sub-par neem, what are the chances they are using a quality emulsifier? 

Making your own neem oil spray solution is the best and most cost-effective way to use neem. Getting a cold-pressed neem oil concentrate ensures you are getting the most potent form of the oil itself. This translates into a solution that will be most effective at getting rid of indoor plant pests. As a concentrate, a little goes a long way and a bottle will last you much longer than a pre-made solution. If you opt for a natural detergent as your emulsifier, then you can rest assured your solution is effective and safe for your plants!

Indoor Plant Pest Control: SNS 209

One of the most inventive ideas to protect plants from pests is to fortify the plant from within, that’s where the genius behind the product SNS 209 comes in. The solution is a combination of Rosemary extract (rosemeric acid) and a few carrier ingredients. Mix the solution with the water you’re going to water the plant with and water as normal. 

The solution will be taken up by the plant and transported throughout its vascular system (all the parts of the plant). Any plant pests that begin to feed on the plant will be forced to also take in the rosemeric acid which is unpleasant to these pests and can even be lethal if they are small or young enough. Those that aren’t killed by the substance will try to move to another feeding spot. This doesn’t work however as all parts of the plant have the solution present.

Physical Control Methods for Indoor Plant Pests

If you’d prefer not to use chemical control methods to rid your plants of pests, you can use physical control methods instead. Two effective control methods are mechanical removal and desiccant application.

Indoor Plant Pest Control: Mechanical Removal

Mechanical removal refers to physically removing offending plant pests either with your hands, an object, or a strong water current. In any case, these methods require you to physically contact each pest or aim a water current (such as a sink faucet or hose) at any pest you can see. The downside of mechanical removal is that it almost never solves the problem and should only be used to knock down pest populations.

Mechanical removal is most useful for pests such as scale and much less useful for smaller pests such as spider mites and thrips. Because plant pest eggs are so small (or are inaccessible in the case of thrips) mechanical removal will almost certainly miss pest eggs. This means that, while the adult population will take a hit, the babies that are soon to hatch will just bring the numbers back up.

Desiccant application involves physically applying a desiccant (such as diatomaceous die-uh-toe-may-shous earth) onto your plants, targeting any pests you can find. The desiccant dries out the exoskeletons and eggs of the plant pests and kills them through water loss. While it is extremely effective, it will kill any arthropods including beneficial insects such as bees and spiders so use it with caution.

The downside to diatomaceous earth is that it is difficult to apply, it inhibits photosynthesis and water loss through stomata, and it can create a white chalky block in the soil of your plant. While it is very difficult to kill a plant with diatomaceous earth, the physical blocking of the plants leaves and the potential pH changes to the soil make it less effective than other control methods. With that said, it can still be a viable option if you’re interested in trying it!

The Easy Way to Identify Indoor Plant Pests

Since most all plant pests are extremely small, visually identifying them is increasingly difficult. To make identification simpler, there are a few products on the market that are designed to help make this process easier. Our favorite is the LINKMICRO LM203 portable digital microscope, and for good reason.

The LINKMICRO LM203 is a portable microscope (there is an option to include a stand which is very helpful) that makes identifying small objects fun and easy. The unit allows you to take pictures and videos if you need to document a pest or a close up view of some object. It also  comes with an SD card that you can use to store any pictures or videos on. 

The close-up images of the plant pests in this article were taken using a LINKMICRO LM203.

Indoor Plant Pest Wrap-Up

There are a variety of plant pests you may encounter among your favorite houseplants from time to time. Knowing how to identify the signs of their presence is important as it alerts you to the problem and lets you know it’s time to act! Luckily, there are various control methods available in today’s market that make dealing with indoor plant pests a bit easier!

Chemical control methods are more effective and, in some cases, simpler than physical control methods at controlling and managing indoor plant pests. Using concentrated neem oil as a foliar spray in combination with SNS 209 for internal pest defense is a wholistic approach to get a firm handle on any plant pest infestation.