I have mealy bugs. They showed up on my house plants about a year ago. At first, I quarantined affected plants in the garage, but it didn't work. They quickly spread to all 3 floors of my house. I've tried multiple brands of pesticides that claim to get rid of them, none work. I've tried changing out the soil multiple times. While I do, I soak the affected plants in rubbing alcohol as suggested by Google search. I rinse them before repotting. The bugs have killed almost all of my house plants, only a few succulents are still alive. It's a bit early to buy replacement herbs and flowers, but I want to make sure these bugs are gone before I do. I would get rid of the rest of the succulents if I thought it would help, but quarantining didn't work. Short of moving, how do I get rid of these suckers?

You have to use the pesticides according to directions. You have to follow up with complete treatments. You can't be lackadaisical.

And once you complete a full treatment, they could come back tomorrow. Once you have them indoors, they get everywhere. Although their lifespan is measured in weeks, they can exist as eggs. Once those eggs hatch, you are in for another battle.
They do not live in the soil so changing the soil won't make a bit of difference.
Quarantine in the garage won't stop the spread.

I HATE mealybugs for just the reasons you have listed. Using alcohol or Insecticidal Soap are your best options for ridding yourself of them, BUT they will never be completely gone. You are in for a lifetime of mealybug eradication diligence.

Most pesticides work only short term as the surviving mealys become resistant and the pesticide doesn't work anymore. Insecticidal Soap and rubbing alcohol are contact sprays that work by softening the shell of insects so they never build up resistance. The mealybugs are not in the soil so repotting is not helping rid your plants of them. But, they are so tiny that they can hide in the pores of clay pots, in the wood grain of your table top and any other surface with a texture. Don't reuse your pots without sterilizing them in a bleach bath or the dishwasher.

Put the alcohol in a spray bottle and drench the plant, every nook and cranny, then blast it with your sink sprayer. Wait for an hour and inspect the plant, spray and rinse again if you see more mealys (they seem come out to replace their dead buddies). Keep repeating until you don't have them crawling out of hidden spots. Inspect your plants daily and then, eventually, every time you water and use a Q-tip soaked in alcohol to get rid of any you see.

Good luck!

I agree with insecticidal soap and alcohol as effective contact treatments for mealies. You will need to do repeated treatments but should see your plants improve over time.

Plants that are under stress for other reasons, such as improper light and water, are much more susceptible to pest infestations. Replacing soil and rinsing roots is one of the more stressful things that can be done to a plant. As Bill noted, it is not an effective treatment for mealybugs anyway. It is likely that those extreme treatments are what has caused your plants to die, not the mealybugs.

Diluted alcohol and liquid dish soap is an effective treatment but only if direct contact with every single mealybug is made. That is not easy to do unless you spray so thoroughly that every leaf and stem and nook and cranny is literally dripping wet. The solution has to wash over all surfaces and into all spaces. It is a very messy task best done outside for that reason. If you are really thorough, one treatment is usually effective. A followup spot treatment might be necessary if you miss a few and catch them early in their return.

That said, you may eradicate the pests but lose the plant to whatever the underlying condition is that is stressing the plants. Healthy plants with proper light and proper watering are quite resistant to most plant pests. That should be your first line of defense and treatment.

My plants are very healthy but, I constantly battle mealybugs - there is no such thing as complete eradication. And yes, a bad infestation will kill a plant, it has nothing to do with the original health of the plant.

I don't bother to dilute or add soap to the alcohol but I do blast the bugs off with my sink sprayer or garden hose for two reasons: First, to get rid of the alcohol so my plant won't be damaged but the second bigger reason... without the alcohol present, more mealybugs will crawl out of wherever they were hiding so I can spray them too. But, if you don't get rid of the mealybugs hiding in the crevices of your pots, you will never get them under control. If your plants are sitting on porous surfaces, you will have to kill the mealybugs hiding there as well.

All I can think is NYC mealybugs are much better behaved and less resilient then what the rest of us are dealing with.

The "pesticides" I've been using have almost exclusively been insecticidal soaps. The only non-soap one I tried was at the suggestion of a horticulture professor. He's also the one that suggested replacing the soil, but only after 6 months of battling these annoying buggers. The plants are in full sun in a greenhouse window with the exception of 2 ferns that only like partial sun. They are sprayed with the soap every evening and then watered. I've been trying to only water lightly as Google also suggested heavily watered plants are more susceptible. Was this wrong? I haven't seen any bugs hours after spraying. After killing a bunch of them, I usually don't see any for a few days, then only a couple for a few days, then large clusters of them, it's about a week and a half cycle. Mind you, all of this is with spraying soap every day. I haven't tried q-tips yet, because I only heard about this when searching the forum this morning. I'm pretty sure the plants did die from the bugs because I see brown spots on my plants directly under mealybugs I've killed (and only under where there were bugs). Eventually, there's just too many brown spots. I am worried about them growing in wood grain. Most of my plants are resting on a wooden windowsill. I didn't want to spray the sill and risk warping the wood. If I spray, but wipe off quickly, will it still kill the bugs? Is there a better way to treat the wood?

I was told this years ago by an inspector from the USDA when I had my nursery, its what @Daisyl said....and its NOT JUST MEALYBUGS but all sap suckers like scale, spider mites, etc....
If you don't knock down the infestation of adults immediately, and then knock down the new emergent next generation immediately, and subsequent hatchings, the survivors will begin to exhibit resistance to whatever pesticide you are using, and you can end up with insects that will not respond to your attempts at eradication.

Th best way to do this is with a systemic. I know there are not a ton out there that are home gardener user friendly, and some of the best were taken off the market for home garden use years ago because they were just too toxic for the average home gardener to be messing with. But there are still some very effective ones, and if you are diligent and do not miss a sequential treatment, you can get rid of some of them...it may have to become a routine part of your plant maintenance, like watering and fertilizing....every Monday, routine pest control.

I grow almost 100% tropical plants, and I have learned over almost 40 years now which ones are more prone to getting infested, with what insect, and what time of the year it happens.
It has nothing to do with the health of my plants, all are kept in tip top shape as far as nutrition, watering, light, humidity and air movement. I pay a lot of attention to those things.

This is the season that ALocasia, colocasia, heliconia and calathea start to get things like mealies and thrips. I am on the lookout, I am doing pre-emptive strikes weekly.

Fall is the season that the Ti Leaves get mealies. I start treating them in late summer to ward off this.

Anthuriums tend to get scale in the late summer/early fall. So I treat starting mid-summer and continue on a weekly basis until spring.

@Daisyl I do the same thing with my hose end sprayer....set to to 'flat' and basically pressure wash the bugs off the plant!

I do like to add something here - there is such a thing as root mealies!! Grow Stapeliads and at one point you will certainly run into 'healthy" colonies of them, I can attest to that.
I think sometimes I need to use a systemic! When placing my C&S in Spring outside, I might add a sprinkling of Bayer's Advanced triple action ( contains Imidacloprid) pellets to the soil, that will work to keep them at bay. And no, I don't worry about the Bees in this case, because they not visiting plants which are not in bloom.

I use Bonide. Its a granular systemic sprinkled on the surface of the soil and dug in. But, I don't dig it in and I don't follow the instructions for amounts, but rather, fill the pot with Bonide all the way to the brim or at least 1/4 inch deep. It works amazingly well but I only use it on the really stubborn infestations in combination with my alcohol spray.

I've never had to deal with ground mealybugs, but, I wouldn't start digging up my plants until I knew that's what I had. I would think using a drench of Insecticidal Soap would help get rid of them - you would have to make sure the drench wetted all the soil or you would miss some. Ursula?

In my hands those Mealies seemed to enjoy Insecticidal soap as a favorite drink!

When I encounter root mealies, I replace all soil! ( hopefully not too often) Now before I replant my stuff, I would soak the affected plants in a systemic, outside of course and according to instruction. Bayer's works great, but one might needs to rotate to a different systemic as the bugs get used to them. You say Bonide works well, which is surely also available as liquid dilution.
Once everything is under control, one might keep a vigilant eye on any "fresh" bug and shoot them with something like Neem oil, available in correct dilution)
I grow a bunch of different Genera of plants together and I think I have the bug stuff under control! Suuuuure! I simply check my plants often from every angle and act immediately when I see trouble!

I don't use insecticidal soap. When I really have to get rid of something that Neem Oil used sequentially won't seem to handle, I use Orthene.

Haven't used it in years, but Orthene did work!!

Its hard to find, but you can get it for commercial size ventures

@Daisyl - I am thinking of packaging and selling the well-behaved mealybugs we have in NYC. You can be my first customer!

Seriously, some years ago I had serious indoor plant pest problems that made me crazy and were also costing me a lot of money. I would treat them and a month of two later they would come back I was sure just to tick me off!

Chemical pesticides were not an option with my clients. It took me a long time to learn that the difference between 98% coverage with a spray and 100% coverage was huge. It is the 2% you miss that survive and reproduce and come back to haunt you and convince you that they can never be completely eradicated.

Thorough coverage means that all leaf and stem surfaces are dripping wet with the spray solution flowing over all of the surfaces. Spider mites can easily survive between spray droplets. It also means having the spray penetrate deep into all crevices. It is not easy and it is certainly messy, but it can lead to complete eradication of the problem. I know that from experience.

Of course, pest problems that get out of hand can devastate a plant. However, my point was that when pests are present there is often an underlying issue. When I find pests on what I thought was a healthy plant, further inspection often reveals that my watering had not been quite as good as I thought it was. As I became more experienced and precise with the care of my plants, it is now very rare for plant pests to appear. I start with good quality plants, take care of them and treat any pest problems immediately before they get out of hand.

My remedies are not for everyone. Imidacloprid can be highly effective and easier to use. Neem works well when applied thoroughly. However, what I am suggesting is an alternative that some folks may want to try.

I have gone as far as pulling a sago palm out of its pot, cutting off all the leaves, shaking off the soil and completely submerging it into a 5 gallon bucket of Imidacloprid for a couple hours. I also soaked the pot for a couple hours. After repotting in new soil, I kept the palm in isolation. The minute the leaves started growing back, they had mealybugs. So much for complete coverage.

In addition to soap or alcohol (my tools of first resort) I have used imidacloprid as a preventive treatment. It's not going to be enough to get rid of an active infestation but it does work to deter new ones. Imidacloprid is an excellent treatment for root mealies in particular.

Speaking from personal experience, there tends to be a human component responsible for mealy bug problems. Or to put it the other way around, vigilance is probably the greatest tool in your arsenal. It's way way easier to deal with bugs when you catch them early. A severe bug problem may reflect errors in cultivation, as Will has mentioned. But it may also reflect a lack of attention.

This human component is particularly important in the resolution of mealy problems. There is no "hit once and forget" solution to these bugs... you have to follow up after the first or second or whatever treatment (twice a week with soapy water) until you see the problem resolved. You have to inspect carefully and double check even after you think the problem is solved.

I'm not an expert but I'm opinionated anyhow, so here goes. I used dinotefuran granules (systemic) combined with topical treatment. The product I found is Ortho Tree and Shrub Insect Control Granules, I'm sure there are others, and it's apparently not available in New York. Dinotefuran is closely related to imidacloprid, so is highly toxic to bees, not for use outdoors or by those looking for a least-toxic treatment. I applied the granules to the soil surface, watered well, then watered normally. It takes about two weeks for the chemical to be taken up by the plant, so meanwhile I used spot treatment with alcohol to knock down the obvious bugs, and to treat the pot and surrounding surfaces.
This is a systemic treatment, meaning it is absorbed through the plant roots and distributed throughout all the plant's tissue. This takes some time--about two weeks in my experience to get to levels in the plant that are toxic to the bugs. I'm not surprised that a soak in imidacloprid didn't work, I don't think it's really made to be used that way. The granules on the soil dissolve gradually and are gradually taken up by the plant, I don't think a one-time soak would do it. I didn't change or separately treat the soil. The plant itself becomes toxic to the bugs, and there's nothing else there for them to eat.
I don't have a lot of plants, but this worked well for me, also got rid of some hard scale, and didn't seem to be toxic to any of the plants--just the bugs. Might be worth a try, but stay vigilant!

I grow succulents ( esp. stapeliads) and mealy bugs can be downright devastating if not controlled. I clean active infestations off plants with alcohol, but like some of the others here, use a systemic rose food containing Imidacloprid regularly. Surface treat all my pots going outdoors in early summer, and again about a month before they come in for the winter. Had an active infestation a few years ago, after moving from IL to IA. Deep treated all my plants by soaking some systemic beads in a gallon of water & then applying it to every pot, in addition to the surface app. It worked. Dealt with a succulent grower in IL for years, that used a concentrate instead that was applied to all of her greenhouse stock, and she often recommended I do the same. The reasoning... the active % in the systemics is quite low in comparison to the full strength concentrates. I've yet to use the stronger preparation. I don't fertilize much, so the systemic does both jobs for me, and has been working. Another tip, keep new acquisitions quarantined from your collection until they've been treated, and are deemed, bug free.