Every seven to ten days I find the same white fluff in the leaf axils and where the petioles meet the stem. I wipe every one I can find with a cotton bud dipped in 70 percent isopropyl and they visibly dry up. A week later there are more, in the same places. Plant is in a 12 inch pot on a moss pole and has been in the house four months. Am I missing a hiding place or is the alcohol just not working?
Quarantine it now if you have not already. Four months in the house means anything it arrived with has had time to walk to the neighbours. Check every plant within arm's reach, especially any with tight growth points, and keep the monstera in a different room until you have gone two clear weeks with zero sightings.
And check anything that shared a saucer or a windowsill drip tray. Mealybugs are slow but they are not immobile, and a shared tray is a highway.
If four to six weeks of manual treatment does not get you there, systemic granules watered into the soil will. They are genuinely effective on mealybugs because the insect drinks the plant. I would only reach for them after the manual approach has failed, and not at all if you have a cat that chews leaves or a toddler who puts things in their mouth.
One correction to advice you will run into elsewhere: do not drench the whole rootball in alcohol to kill root mealybugs. It damages fine roots badly. If you suspect them at the root, bare root the plant, rinse the roots thoroughly under lukewarm water, and repot into fresh mix in a washed pot.
Agreed. Bare rooting sounds drastic but a monstera shrugs that off far better than it shrugs off solvent poured over its roots.
Write down the dates you treat, on your phone or a sticky note on the pot. Everyone thinks they will remember and everyone drifts to twelve days between treatments, which is exactly long enough for the next generation to mature.
@sashiko_sam · 5mo ago · 3 replies
Mealybugs, and you are killing adults while the eggs hatch behind you. Alcohol works well on contact and does essentially nothing to eggs, so a single pass is always followed by a fresh crop about a week later. That is the loop you are stuck in.
What clears them is repetition on a schedule for longer than feels necessary. Treat every 5 to 7 days for at least 4 to 6 weeks, and keep going for two more treatments after you stop seeing anything at all.
Places people miss, roughly in the order I find them:
Rotate what you use rather than relying on one thing. I alternate isopropyl on a bud for spot work with a full spray of insecticidal soap or horticultural oil that coats every surface including stems and pot. The full coverage spray is the step most people skip and it is the step that catches the crawlers you cannot see.
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@wind_down_wren · 5mo ago
The moss pole point deserves more attention. I fought mealybugs for five months, finally unwrapped the pole, and found a colony living in the damp sphagnum that no spray was ever going to reach. Replaced the pole and it was over in three weeks.
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@rest_day_rita · 5mo ago
Worth adding a shower rinse before each treatment. Blasting the plant with lukewarm water knocks off a good share of the crawlers physically, so whatever you spray afterwards has less to do.
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