This topic is pretty much something a lot of people do not want to discuss or deal with but if you own a lot plants, you're going to get pests, plain and simple. This is something all plant parents deal with and once you accept the fact that it's going to happen, the easier you can deal with them.
Common houseplant pests such as mealy bugs, fungus gnats, thrips, and scale can often find their way into our personal collections and can show up on new plants that arrive at my shop too. It's inevitable, but learning the signs of pest damage will help you start identifying what is going on with your plant and then you can take the desired action to treat it.
Getting a houseplant pest does not make you a bad plant parent! Pests are simply a part of plant ownership.
Let's start this with a popular question I get asked a lot. Where do plant pests even come from?!
Houseplant pests can come from all sorts of places truthfully. However, the main reason you see pests appear on your houseplants is because, well, they are inside your house. If you think about it, the fact that we take plants out of natural environmental elements such as rain, wind and sun, it then puts the plant in a weaker state than what it would be outside. A houseplant could have a pest on it outside, but typically natural predators take care of it. Having plants indoors will basically take away all those environmental factors and allow even a tiny pest to spread quicker than usual.
Now since we know the basic answer of where houseplant pests come from, there are definitely more ways they can enter your home. Flowers, produce, soil, outdoor plants, they can fly in through windows or open doors, ants and other typical household bugs can even bring them in. We as humans can even bring them in, on our clothes or shoes!
So how can we control them?
Well let me preface what I'm about to say with this, if your infestation is small and you just noticed something off with your plant, isolate it immediately. A small pest problem can easily be eradicated with a soft treatment first, rather than dousing it in harsh chemicals.
While the remedies I suggest below seem easy peasy to just spray and be done, there's always the chance of overdoing it or you have a plant that has a bad reaction to treatment. If you're worried of a certain pesticide, consider spot treating a couple leaves, then observe how the plant reacts to it over the course of a day.
PRO TIP: Never spray your plants with pesticide in the sun, it will cause a reaction on the foliage and burn it up
Different pests require different treatments so I will break down the most common pests and their treatment path.
Maybe one of the most common houseplant pests, they are fluffy, white and have long antennae. They are easily seen on green foliage and can cause quite a gross-face reaction when you find them. They typically hide in the nooks and crannies of your plants but sometimes venture out on top of a leaf to be seen by you when you walk by! They cluster together on the stems where a leaf emerges so they can stay semi-hidden.
Spraying the whole plant with water will help dislodge the big clumps and spot treatment of alcohol or neem oil will also help eradicate them. If your plant is small enough, soaking/submerging the plant in an alcohol and water bath will 100% dislodge and kill a small infection. Mealy bugs can be a tad difficult to treat if they infestation is not controlled quickly, they can spread to other plants fast but the damage they cause is quite minimal. They are more gross to look at than damaging to the plant.
Ah fungus gnats, clearly one of the more annoying houseplant pests known. These little dudes are super frustrating and absolutely one of the most popular pests to arrive inside your soil and sometimes you don't even know they're there until the eggs hatch and become adults. Gnats nest in damp soil and easily spread from plant to plant. However, as annoying as they are, they are not damaging to your plant like some other pests.
A few notable treatments are available for these pesky little buggers but most importantly, let your soil dry out as much as possible. Fungus gnats thrive on moisture and will die if standing water is not available. Another option is to water your infected plant with 1 part hydrogen peroxide and 1 part water. Let the plant sit for a few minutes, then water thoroughly with water only to flush the peroxide out.
PRO TIP: If you aren't sure where the fungus gnats are coming from, consider using yellow sticky traps on a few plants, then you'll see which sticky trap has the most action on it (aka dead bugs) and that is your culprit!
Scale looks like small to medium-sized, hard brown bumps on your plant. This pest is stationary and you will probably never see them move but inside those hard shells are insects sucking the life out of your plant. Random clusters of brown lumps could be scale. If you aren't squeamish, run your fingernail over the bumps and pop one off, if they pop off easily, it's scale.
Bad infections will make the surface areas around the plant sticky, such as the floor or walls. This is a tell tale sign of a nasty infection and you must take the plant outside or away from everything else as quickly as possible.
Treating scale is fairly similar to treating mealy bugs. For small infestations, dip a q-tip in rubbing alcohol and poke the scale with it. It should immediately die and stick to the q-tip. For larger infestations, spray the plant thoroughly with insecticidal soap or neem oil. Allow that spray to sit for a bit and then spray the plant aggressively to dislodge any of those sticky creatures. Rinse and repeat as needed.
Teeny tiny little round tan insects that leave a silky thin web around the crevices and nooks of your foliage. These little suckers are quite common but honestly one of the easiest pests to deal with if caught in time.
Use insecticidal soap to thoroughly soak the plant, making sure to get nooks and crannies and undersides of leaves. Allow that spray to sit on the foliage for a while, then wipe away as much visible webbing and mites from the plant that you can see. Spraying the plant with water vigorously will help after treatment. Rinse and repeat as needed.
PRO TIP: Spider mites are more attracted to sensitive foliage such as Palms, Calatheas and Alocasia.
Thrips are small thin brown/black winged insects. You usually will not be able to see thrips with your naked eye as most are under a millimeter long. Blotchy reddish/brown discoloration on the foliage is usually an indication that a thrips infestation is present. They have no natural predators so they can quickly multiply and cause significant damage. Out of all the common houseplant pests, thrips are probably the most challenging to deal with if not caught early.
The first step you'll want to do is isolate the plant and spray the plant pretty heavily in the shower or outside to dislodge any bugs. Follow this with an insecticide, such as neem oil or Captain Jacks Deadbug Brew. The main substance, Spinosad, is great for dealing with Thrips but is quite toxic. You will need to repeat this action several times as the adult thrips lay eggs every 10 days or so. If the infection continues even after taking care of any foliage problems, you may want to consider a soil systemic to kill any eggs that are in the soil.
In conclusion, pests suck but you might as well get used to them if you're going to have plants around. It's not if they arrive one day, it's when. But now that you have a bit of knowledge in your back pocket, you'll be a pro at spotting a pest by the signs, or damage, and taking the proper steps to put an end to them. Good luck!