Mealybugs :( need repotting advice for multiple species of orchid :(

[yeoshua88]

So I have been aggressively fighting a mealy bug infestation for about 2 months now. It came in on a new paph that I bought and before I noticed the infestation it had already spread to a dendrobium nobile and 2 of my phals including a schleriana. I have gotten the infestation "controlled" in the sense that I have not seen any mealybugs on any orchids other then phal schleriana in about a month now (even the origonal paph). The poor schleriana has gotten so stressed that it started putting up a keiki 2 weeks ago which I have never had happen to one of my orchids before and that keiki is the only spot that I have seen any mealy bugs and it has only been nymphs. I have not seen any on the long leaves in about a month. I have been switching between isopropyl alchohol, a pyrthrine based insecticide, and neem oil doing ~once a week for 3 weeks before starting the next treatment. I have also been watering all orchids seperetly to prevent eggs/nymphs from being transfered between orchids during waterings. While I have it controlled now if I keep fighting like this the mealybugs probably will have a massive outbreak infestation again due to resistance so now is probably the best time to repot since I have a few resistant bugs isolated to one orchid currently. I would rather repot now then wait for the resistant bugs to grow out of control. I should repot all orchids that are in the potential infection zone which sadly is 7 orchids (I have 3 phals, an oncidum, a zygo, and a paph that all could theoretically be infected due to proximity and cannot be moved due to my apartment set up. I have been treating all orchids like they are infected even if no bugs were seen on them and have not seen any on the oncidum, zygo, and one of the paphs even with me looking extremely closely almost everyday.

The phals are all putting up spikes right now but are extremely well established so probably will be fine for repotting because I think a nuclear accident could not kill them. I however, now find myself in the situation of having to repot a dendrobium, paph, zygo, and oncideum which I have never done before and am extremely nervous to have to do this all at once.

I have heard that zygopetalum in particular tend to just die if repotted at the wrong time. The zygo is currently putting up new shoots and roots so from my understanding this is the absolute worst time to repot and it will die if I do it now. Any advice on how to repot all these orchids species for the first time would be greatly appriciated.

Sorry for the long post.

[estación seca]

As you're finding, mealy bugs can be difficult to control. Adults crawl far away from the plants to lay eggs, which can remain viable for two years. It is highly likely all your plants have bugs, and you will have issues for some time.

The time to repot almost all orchids is just as new root growth begins. How long are the new roots on your Zygo? This might be the ideal time to repot. However, repotting will not eliminate mealybugs.

Paphs. and Phals. can generally be repotted at any time. Realize Paph. roots are brown and fuzzy, different from other orchid roots.

I would not repot the others out of season. Dens. and
Oncs. also should be repotted just as new roots begin. In my opinion repotting out of season is worse for them than a controlled mealy bug infestation.

Don't use oil sprays frequently. They clog the plant's stomata and can cause problem is used too often. Once or twice in a few weeks is probably OK. Neem oil will not eliminate mealybugs, likely because you can't get it into all the crevices.

Most horticultural mealybugs have substantial resistance to pyrethroids. If you've tried them and found dead mealybugs, you can keep using those.

We are going into winter, a difficult time for orchids in homes. I suggest controlling them over the winter, then attempting definitive treatment when it is good and warm next Spring. Pay frequent and close attention to your plants. Keep a spray bottle with alcohol next to your plants. If you see mealy bugs, spray the infested area with alcohol.

Many people here use pesticides. I submerge my plants in water with a tiny bit of soap added to break the surface tension. If you perform an advanced search here on "mealybugs" and my partial username "estaci" you will find my posts. But I do this during warm weather, during the growing season. I wouldn't do it during cool weather.

[yeoshua88]

So pretty much you are saying that it is unlikely that even a repot will get rid of them all and I should continue spraying them like I have been until they are gone or until the spring.

I have had mealybugs only once before and it was on one of the phals that probably is infected now sadly. It was many years ago when I picked her up off the street and it did take about 6 months of treatment before I finally killed them all. I feel like I almost have complete control right now which is annoying because I seriously have not seen any activity on my other orchids besides the schleriana right now. I do have an alcohol spray bottle that I use as a spot treatment for when I see individual insects. I do not think the pyrethrin insecticide worked much at all which is why I transitioned to neem oil which does appear to be working. I do not see the dead insects normally but as I said I have not seen any adults on long leaves since initial treatment with neem oil.

[RJSquirrel]

try a bag of lady bugs in your garden. you have to let them out at night so they stay put.

The mealys will hide in blooms around the stem inside the folded leaf. Around the base of the plant and any leaf fold up through the top of the plant.

I only recently got mealys imported to me. fortunately, I found them before they became a problem. Did mail the vendor to let him know he may have a bigger problem than I had.
Just a heads-up kind of thing. Mealys can happen to anyone who doesnt do a walk about of everyone of their orchids with a jewelers glass everyday.

good luck beating the boogers up!!!

[Ray]

You're not being nearly as "aggressive" in your treatments as you think, and may actually favor the development of resistant strains.

Don't switch between treatments weekly. Instead, get a good insecticide labeled for mealy bugs.

Spray every exposed surface of every plant to dripping AND drench the potting media.

Repeat that complete treatment two additional times at one-week intervals.

If, in about a month, you see the return of the infestation, repeat that complete 3-week process using an insecticide having a different mode of action. This document might be of help.

[yeoshua88]

I am doing each treatment for 3 weeks before switching so it is once weekly for 3 weeks then switching. So I am doing what you recommend sorry if that was not clear.

[Ray]

Thanks for that clarification.

Are the treatments as thorough as I recommended?

Most insecticides only kill adults, leaving eggs and juveniles alone and able to mature.

None of the three treatments you have used is particularly effective against mealies. If they were, your issue would be eliminated by now.

When my plants are outdoors, I use acephate as my "go to" treatment. Indoors, I primarily go with OrganiShield, and if I need a third tool in the kit, the BioAdvanced 3-in-1 Insect, Disease, & Mite Control from my local Lowes or Home Depot.

[Leafmite]

I use isopropyl alcohol on my citrus and indoor strawberry plants and it is pretty effective if done weekly and on the entire plant...and any neighbors. Phals seem to provide safe hiding places for mealies which is why I only have two of them and I keep them far from the citrus. I do not use any pesticides indoors.
Even with the alcohol, I have to be careful that the spray does not drift onto my carnivorous plants, towards the parakeet, or into my cherry shrimp tank.