How to get rid of mealybugs on indoor plants
"It's so fluffy!" But unlike the movie Despicable Me (where Agnes loves her white, fluffy Unicorn soft toy), if you see fluffy, white bugs on your plants it's nothing to celebrate. The good news is there's a very effective 3 step method that will get rid of mealybugs on your indoor plants.
Mealybugs are a pest both indoor and outdoor gardeners have had to contend with for over 100 years. It feels like there's a remedy for each of those 100 years, but the good news is there's one 3 step method that CAN rid your indoor jungle of mealybugs.
However these guys can be some of the most difficult pests to completely get rid of, which makes sense once you understand their lifecycle, as well as where they like to hide out. But it absolutely can be done with a little patience, especially if caught early.
What do mealybugs look like?
There are a few types of mealybugs but the one you'll most often see attacking our indoor plants is the longtailed mealybug like these guys below, called Pseudococcus longispinus.
They are small, white, and appear fluffy, but are actually covered in a powdery wax that repels water-based insecticides (which is why you need a different approach to other insects, and why what you've tried so far might not have worked).
They also like to hide out in difficult to treat areas. They are pretty easy to spot as adults can reach 3mm to 5mm long. If you don't see any adults you might first notice white 'fluff' in the crevices of your plants, like this below.
What conditions do mealybugs like?
Mild temperatures and high humidity are the conditions mealybugs love. Eggs hatch every 2-3 weeks (which is why repeating treatment at least every 2 weeks is required). Extended periods of hot weather will reduce their numbers.
Are root mealy the same?
You might also have heard of root mealybugs or 'root mealy' which target roots. Because they live below-ground, treatment of root mealybug is different from the more common longtail mealybug, mainly found on foliage and flowers. If you're on a mission to get rid of the longtail mealybug above-ground, this guide is for you.
How to treat mealybug on indoor plants
No matter how bad the infestation, the first thing to do is move that plant ASAP. One infested plant can quickly turn into your whole jungle becoming a victim to mealybugs. No thank you!
Once your plant's in isolation (for plants you can move of course), the most popular method to kill mealybug on plants starts with getting yourself some isopropyl alcohol, also called rubbing alcohol, but it's important to know the difference between the two.
Should I buy isopropyl alcohol or rubbing alcohol?
They are the same thing, however the concentration is different. Isopropyl alcohol (also called IPA) is 100% vs rubbing alcohol which is diluted, usually to around 65% to 70% isopropyl alcohol. It's the diluted one - called 'rubbing alcohol' - that you want to look for. But as a back-up, you can also dilute the 100% concentration as another option.
Where can you buy isopropyl alcohol or rubbing alcohol from?
The one I use is Isocol Rubbing Alcohol (if you're in New Zealand). For my international plant friends, the Amazon Basics 70% Rubbing Alcohol will do the job nicely. If I'm sold-out - or you want to get yours in-store instead of online - most chemists and hardware stores are likely to either have 100% isopropyl alcohol or rubbing alcohol.
The 3 step method for killing mealybugs
You can (and should) use the alcohol method two ways as it's most effective when both methods are combined.
The first step is to kill the adult mealybugs. Dip a q-tip, cotton bud, cotton ball or cotton pad in rubbing alcohol (not 100% isopropyl alcohol). Press that on to every adult you can find, wiping them off the leaves as you go. It works instantly and those evil fluff-balls will turn orangey-brown when dead.
The second step is to mix 1 part of rubbing alcohol with 1 part water, and a couple of drops of liquid dish soap. Stir well and put that mixture in a fine-mist spray bottle. I like the Mister 360 super fine spray bottles (those are available in NZ), which is the same as this Ultra Fine Spray Mister (that one's from Amazon). You need the finest mist possible as it's important to get really good coverage.
Spray everywhere! Leaves (top and bottom), stems and lightly spray the top of the soil too (don't pour it onto or through the roots however). Get that mixture into all those leafy nooks and crannies. That waxy coating makes mealybugs almost water-proof, so the addition of that small amount of liquid dishwash soap (same as you use for washing up), helps the spray get through that waxy layer.
It's important with this method that you rinse the plant thoroughly afterwards as it is a strong treatment. Wait between 5 and 10 minutes maximum before completely washing it off. I do my treatment in the bath or shower so I can use the shower head to wash off the treatment - and every dead mealybug along with it!
TIP: If the rubbing alcohol or isopropyl alcohol you find has a bit less than 70% alcohol that's still fine to use for both steps above (the one I use is about 64% alcohol but that one from Amazon is 70%). You just don't want to go over 70% without further diluting the alcohol. Make sure you do a test patch first if your plant is sensitive or if you're unsure how your type of plants reacts to alcohol or to dish soap.
Should you repot when a plant has mealybugs?
Yes, if the infestation is really bad, or you just want to do everything possible to get rid of the mealybugs as thoroughly and quickly as possible, the third step is to repot. You don't have to if you're concerned about how well your plant will recover, but it is recommended. Remove as much of the old soil as you can, focused on the top 5cms or so of soil as that's where the eggs and larvae concentrate.
Rinse the roots well, especially focused on the base of the plant. You don't have to remove every particle of soil. While you're doing that, it's really important to give the nursery pot and cover pot a good clean and sterilise too. Give the pots a scrub and 'bath' either in a bleach solution (I use 1 part bleach to 10 parts water), or using hydrogen peroxide, to make sure any sneaky mealybugs are gone-burgers.
Hydrogen peroxide can be used both to kill what's in the soil and to clean the nursery pot and cover pot. I use Oxygen Plus 3% Hydrogen Peroxide in New Zealand, which is at the right strength for use with plants. If you're not local, have a look for Essential Oxygen Food Grade Hydrogen Peroxide 3% (available on Amazon).
After rinsing the roots, to kill what's left, water with a quarter cup hydrogen peroxide 3% to 4 cups water and pour over the roots before repotting. To clean the nursery pot and cover pot, scrub off surface soil, then mix 1 part hydrogen peroxide 3% to 1 part water in a tub or bucket. Fully submerge the pots in the cleaning solution. Leave them in the mixture until the solution stops bubbling. Remove them, rinse well, then leave to dry. You can re-use the same nursery pot and cover pot right away once dry, or repot into new pots.
Do you have to repeat treatment for mealybugs?
Yes, these guys are great hiders. You will need to repeat steps one and two every 10 days to 2 weeks on average at least one more time, so you will treat your plant at least twice in total. Use a cotton bud on any new adults that have emerged, then spray and wipe down the leaves again.
If you can't see any signs of mealy bugs having come back, or want to be proactive to make sure your jungle remains a mealybug free zone, Conqueror Oil is superb. I use the Yates Organic Conqueror Oil. Mix 10mls Conqueror Oil per 1 litre water. Use that mixture to both wipe down the leaves and spray thoroughly over the plant and around the base. Note that some plants like hoya don't like oil on their leaves. For them, skip this step, or use a systemic like Groventive (in NZ) or Captain Jacks Systemic Houseplant Insect Control (overseas) instead.
How long should you wait until a plant can come out of isolation?
Whether you repeat the alcohol treatment, use Conqueror Oil or Groventive, repeat that first treatment at least one more time, then wait at least 2 weeks with no signs of mealybug before returning your plant to joint the rest of your jungle. All up, expect your plant to be in isolation for at least 4 to 6 weeks.
How to stop mealybugs coming back
If this is old news to you, and you got rid of them only for mealybugs to come back again (and again), you can also use a systemic insecticide. The fastest method is a contact insecticide, like the rubbing alcohol method above, but a systemic works longer-term.
A systemic works from the inside to kill biting and sucking insects like mealybugs. Best used at first signs of an infestation, however it will take longer to work so is best used along with a contact insecticide. The systemic I use is Groventive (if you're in NZ), so follow that link to read more about how it works and how and when to use it. For my international plant buddies, you'll want Captain Jacks Systemic Houseplant Insect Control (available from Amazon).
Can you repel mealybugs to prevent getting them in the first place?
Yes, if you want to be pro-active, but don't see any signs of mealybugs in your plants right now, you can use neem oil as a natural repellent. I use the BioNeem neem oil as it's much higher in the active ingredient that repels pests, including mealybugs. Diluted neem oil (like the strength used in leaf shine products), won't be strong enough to be an insecticide, just a mild repellent. You need commercial strength neem (like BioNeem is).
Before you treat
The same 2 warnings apply when treating any type of bug, whether using a DIY method, home-made or store-bought: some plants are more sensitive than others. If you know the plant you're treating has a reputation of being more sensitive, or you're not sure, only treat a small area on the plant first, wait at least 48 hours, and providing all is well, you can go ahead and treat the entire plant. Common ones to watch for are ferns, succulents, orchids, begonia and peace lily as well as thinner-leafed indoor plants like stromanthe and some hoya.
Remember also to always keep the plant out of direct sunlight during treatment as sunlight + treatments can sometimes combine to scorch leaves until they've dried, usually a concern when using an oil-based treatment that can leave a residue behind and make plants temporarily more photo-sensitive (meaning they are temporarily more sensitive to light). It's best to treat early morning.
Quite literally, that's how mealybugs feed on your plant. If your jungle keeps getting targeted by pests in general, I'd highly recommend adding silica to your entire jungle's feeding schedule. In NZ the best two I've found are GT Silica or Dyna-Gro ProTekt. I'm not sure on sourcing GT overseas, but you can get Dyna-Gro ProTekt from Amazon internationally as that's an American brand.
Silica helps plants create a barrier against future attack from chewing and sucking insects, helping protect roots, stems and leaves, while helping plants recover and heal faster. Silicon helps protect the rest of your jungle from attack also. It's nature's bodyguard for our indoor plants! Generally outdoors plant gets all the silica they need from soil water naturally, but indoor our plants miss out.
The sooner you start treatment for mealybug the better. I hope you're reading this 'just in case' but if you do have a mealybug infestation, now you're armed with the most effective method to kill mealybugs, as well as the ways to prevent them from coming back.
Remember eggs hatch about every 2 weeks so make sure you repeat this treatment at least once a fortnight later, and keep infested plants away from the rest of your jungle in the meantime. It can be done (with a little patience). Best of luck.
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