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I’m going to start by giving you a little advice that will both help and horrify you:
Once you have house plant pests, it’s super hard to entirely eradicate them if you have a lot of plants.
So check your plants often and spray with neem oil as a preventative.
Where do houseplant pests come from?
They come either on plants we’ve bought or in the soil of new plants.
Or on our clothes, hair, pets.
If it comes into your home, a pest can hitch a lift on it.
However, if you create the right conditions, they’ll just…show up. Especially fungus gnats, but that’s ok because apart from being annoying af, fungus gnats won’t really damage your plants.
Do check your plants when you buy them – especially if you buy plants from the reduced section. Often the rather sad, yellowing reduced plants have simply been overwatered, but always check.
Check reduced orchids especially carefully. They often have a mealybug or two hiding behind the flowers.
Type of houseplant pests & how to identify them
There are various different types of houseplants pests, but I’m just going to cover the main offenders: slugs, mealy bugs, spider mites, aphids, scale, and thrips.
Yeah, you’d think I was joking but I’m not. This is more specifically aimed at those of you that keep plants in terrariums. It’s not at all uncommon for slug eggs to wind up in the substrate or potting mix.
I know, because we once had a fish tank that was half water and half, er, empty, with a pile of mossy rocks that stick out of the water.
We added the moss and a peperomia piccolo banda that I’d been propagating. I was interested to see if it’d grow (it did).
A sunflower seed also ended up germinating in there (we assume it came from the birdseed we keep in a bin next to the tank). After a tiny baby slug ate the sunflower (which had grown beautifully – at time of death it had four leaves) and then moved onto the peperomia, who has since been moved to a safe house (a jar of water) and is now in witness protection.
The annoying thing is not only had I seen the slug, I’d taken a photo of it eating the sunflower and sent it to my boyfriend. By the time Dave messaged me back saying ‘GET IT OUT’ the little bastard had gone, NEVER TO BE SEEN AGAIN. We just noticed the plants decreasing in size and a lot of slime.
At the time of writing, he’s still at large.
How to identify slugs:
- they look like fuckin slugs
- Slimy af
How to get rid of slugs:
- Find it (harder than you’d think)
- Chuck it outside (we’re not monsters)
- If you are a monster and want to kill it, take it to the nearest duck pond or similar and feed it to a duck. They love ’em. Slugs are toxic to most other animals, even hedgehogs that are falsely rumoured to eat loads of them, but ducks are hard and can handle them
Mealybugs love succulent leaves, so they love, er, succulents. However, they’re also partial to Hoya. They will infest most plants, but they love juicy leaves.
They’re a type of scale insect, so whilst they move more than scale, they barely move at all.
If you have something that looks like a mealybug but you can see it moving, it's probably a Cryptolaemus montrouzueri.
These things are actually mealybugs predators, and they’re extremely efficient.
How to identify mealybugs:
- They leave a white, cotton wool-like substance behind. I daren’t look up what that stuff actually is, because it’s probably something gross.
- The actual bugs look like little grey woodlice.
How to get rid of mealybugs:
- Dab the adults with surgical spirit.
Although I don’t have any surgical spirit – mealybugs have barely any molecular integrity, so a gentle poke with a cotton bud kills ’em.
It doesn't make me feel like a very good vegan though. What am I meant to do though? Put up a sign warning 'all ye that enter here will get poked to death with a cotton bud'??? MEALYBUGS CAN'T READ.
- Spray the plant down
Just plain water will do – you just need a decent jet so you can blast them off. If you want to add extra bite to your spray bottle, fill it with water and add a drop of dish soap, castille soap, or neem oil.
Warm water helps to emulsify everything together.
The life cycle of a mealybug lasts a couple of weeks, so spray every four days or so for a month to get rid of the bugs entirely. Although mealybugs are expert hiders, so keep an eye out for stragglers.
Keep a close eye on your plant until you’re certain they’re all gone
Spider mites SUCK (both literally and figuratively) and they’re TEENY TINY. The image below is from a microscope, so you’ll spot the damage before the mites.
The only way you can see spider mites with a magnifying glass is when they start to make webs and increase in numbers. By this time it’s not too late to save the plant, but a lot of the leaves will be effed and the spider mites will most likely have spread to other plants.
The damage looks like this:
They’re not to be confused with regular spiders, whom I encourage to make webs on my plants to reduce fungus gnats.
Spider mites PREFER hot, dry environments, but they are MORE THAN HAPPY to turn in a damp house in the middle of winter.
How to identify spider mites:
- They’re tiny red, er, mites.
- They spin webs, which is easier to see than the mites themselves
- You may see spots on the leaves, or even get a lot of leaf drop.
- Often you can see little white specks on the undersides of leaves before you see the webs and the mites
- If you suspect mites, wipe down the underside of the leaf with a damp paper towel. If you get orange spots/streaks, there’s a pest presence.
How to get rid of spider mites:
- Predatory mites are awesome for spider mites
- Spray neem oil on the plants – like with mealybugs, it disrupts the mite’s hormones and stops them from eating and reproducing.
- Insecticidal soap – the DIY bug spray I mentioned above will work too.
Spider mites have a life cycle that’s nearly 2 months long (51 days I believe) so you need to keep up your spraying regimen for a long time.
I spray every other day for a week or two and then decrease it to every few days.
Showering them in tepid water is a great way to get rid of the webs and larvae.
You can also soak them in a hot bath – I’ve outlined the process here.
I hate aphids. They do a TONNE of damage quickly. They do tend to stick to the same types of plants though. They’re very partial to new growth on ferns, and ironically enough, love to eat carnivorous plants.
Whilst they’re difficult eradicate on the plant they do target, they don’t seem to be interested in my other plants.
How to identify aphids:
- They’re small, green or black, and round
- Some fly, some don’t. It depends on species of which there are 4,000 (!!), 250 (!!!!!) of which are pests to plants
- Apparently, it’s common for ANTS to BRING aphids inside. Thanks guys!
How to get rid of aphids:
- Wash your plants with soapy water – Dr. Bronner’s is a good one that won’t kill your plants.
- Neem oil. Obvs. I think a big takeaway from this post is that we all need some neem oil. It smells like peas and gravy.
- Predatory mites – ladybird larvae are voracious aphid hunters.
- Birds also like aphids, so you can try putting your plant outside
I’ve been lucky enough to avoid a large-scale scale outbreak, but a LOT of people struggle with scale on their Monstera, and every single palm I’ve ever bought from Ikea has had them.
There are loads of different types of scale, but if you have a lot of weird flat things on your plant that scrape off pretty easily, you may have scale. They can appear on the leaves and stems of the plant.
How to identify scale insects:
- Black dots on the base of the stem
- The adults literally look like scales on the plant.
How to get rid of scale insects:
- lf, like me, you’re a picker by nature, arm yourself with some tweezers and tweeze those suckers off.
- Surgical spirit/rubbing alcohol. I don’t think there’s much that wouldn’t work on, but try not to get it on your plant too much, because it can damage it.
- Castile soap
- Neem oil
- Prune it. This can be the only option to dramatically reduce the number of bugs.
- Predatory mites – lacewing larvae are a good option
- Scrape the eggs off the stem
I hate thrips. Whilst they can live on plants and not do too much damage (though this isn’t a given), they’re really hard to get rid of.
How to identify thrips
The larvae are tiny lime-green worms that look like tiny rice grains. The adults look kinda like thunder bugs – black and skinny.
How to get rid of thrips
- Constant vigilance – they will disappear and reappear for no discernible reason. I can only assume they can move between dimensions.
- Physically remove them – shower them off or just wipe with damp kitchen towel
- Spray with neem oil, castile soap, and/or water. Every few days. Possibly forever.
I have thrips on my Monstera deliciosa that come and go and don’t do much damage. But they’ve ravaged my Thai Constellation and I can’t get rid of them 100%.
Thrips damage looks like this:
Ok, not a bug, and you can’t use insecticide on them (but you can spray them with water).
If you’re seeing bite marks out of your plants, make sure it’s not your dog or cat before investing in bug killers.
I’ve read that cats especially love African Violets, for reasons they’re yet to disclose. Oh, and spider plants can get them high.
I have a rabbit that is 100% likely to eat any of the house plants she can get her paws on, so we keep them apart. My mum’s dog likes to have a nibble on some of her plants, so they’re kept up a height. Don’t assume your pet will respect your plants.
Should you use chemical or homemade bug spray?
I prefer homemade.
The trick to getting rid of houseplant pests is persistence, NOT what you use. If you’re diligent, you can get rid of pests using just water just as effectively as using bug spray.
Also, chemical pesticides aren’t great for your lungs, so you need a mask. I need to reduce barriers to tending to my plants so having to get a mask would inevitably deter me from debugging them.
Keeping a spray bottle of castile soap ready at all times is great because it’s gentle and doesn’t separate as neem oil does.
Pests can actually become immune to pesticides, so don’t get too reliant on them. Thrips are particularly quick at adapting to them.
What about systemic pesticides?
I have a article dedicated to systemic pesticides.
Systemic pesticides are added to your house plant soil (they’re usually granules, and you can often just water them in. They work in a few different ways, but they basically get absorbed by the roots so when the pest eats the plant they get poisoned.
I don’t use them.
The main reason for this is that the brand I see talked about the most is Bonide, which isn’t available in the UK. Our systemic are weaker, to the point where they’re pretty ineffectual.
Would I use systemic pest control if I could get it?
Probably not. Soil health really helps with plant growth, and healthy soil has a lot of beneficial microbes and bugs that would be decimated by systemic pesticides. A prefer a more natural approach.
Tips for deterring and repelling pests.
- Bottom water
This is a great way to reduce fungus gnat numbers.
Watering plants from the bottom allows you to keep the top of the soil dry, so fungus gnats won’t want to lay their eggs in it. It’s just not a very attractive environment for them.
- Clean the leaves with neem oil
Neem oil is better at preventing pests than killing them, because it work by affecting the hormones of the pest not by killing it on contact. Neem deters pests, so by spraying the leaves down when you dust them, you can stop them from ever turning up in the first place.
Neem oil doesn't negatively affect most beneficial bugs except for bees. I'm assuming you don't keep bees in your house so you'll be fine, but be aware of this if you're using neem oil outside.
- Diatomaceous earth
You can buy it on Amazon. Sprinkle a layer on top of your houseplants to stop the baby bugs from being able to get out of the soil.
Good grief, I went onto Pinterest to look up the uses of diatomaceous earth and people EAT IT. They EAT IT.
Ok, now I looked up what it actually is and it’s BABY PLANKTON.
Oh wait, they’re fossilised. I suppose that’s ok then.
It kills beneficial bugs too, so be aware of that if you’re going to use it – perhaps try grabbing a ladybird or two first.
- Beneficial nematodes
Nematodes are tiny wormy things that eat pests, and they’re great at getting rid of fungus gnats. I have an article all about them here.
- Check your plants diligently
I don’t adhere to a weekly watering schedule as it can lead to overwatering, but I like to check my plants over once a week to check for bugs, what the new growth is like, and whether or not they look like they’re having a good time.
This is especially important coming into winter, since pests can get a foothold more easily. Winter growth is generally weaker and more susceptible to getting pests, and the plant can’t recover as quickly when it’s not growing.
If you do notice a couple of bugs or even a full-scale infestation, the first thing to do is to move the plant into isolation.
(Unless, of course, you have a fiddle leaf fig, in which case you have to move all the other plants away to isolate it, for if you move a fiddle leaf fig it’ll have a massive hissy fit and drop down dead).
Physically remove as many of the bugs as you can using tweezers or a cotton bud. Mealybugs and scale especially love to get right into the crevice of the plants so be sure to check over thoroughly. If you’re unsure you can get them all, stick your plant into the shower and give it a gentle, tepid shower before spraying it with your bug spray.
If you’re interested in how the hell I manage to keep 100+ plants alive, read this post.
Bugs that aren’t pests
I have no pictures, because, er, I’ve never had any BUT don’t assume all bugs are bad, there are some that will help you:
Earthworms – they’ll stop your soil from getting compacted AND they’ll poop out worm castings, which is a very effective but very gentle fertiliser.
Springtails – little white dots that will eat any fungus – like fungus gnats but WAY less annoying
If you have a lot of plants, you’re going to end up with pests at some point. Starting preventative care now, and deciding how you’re going to treat them will help you respond quicker when the time inevitably comes.