Tricky when growing indoors. I had some success with using a Bayer systemic which contains this ingredient: Imidacloprid. It is a granular time release. It is in a few of their products, Rose and Flower Care, Shrub, etc. But it must contain that ingredient. Check the label.

It works slowly through the roots and will kill off any sucking insects. I used it as a last resort on scale which spread to many of my plants and I was unable to clear up by simple, organic methods.

I would not use it inside the house unless you are certain pets and children will not have access to the plants. It is granular and stays on the surface of the media.

I would use it outside on my orchids. I would spray the upper plants with Neem Oil or another oil type insect spray. Neem smells horribly but is safe around pets and children. The foliar spray will kill off the adults, the Bayer product will take care of the eggs and baby stage. It will travel up into the plant and keep any further infestation.

Bayer does have a spray containing the same ingredient but should only be sprayed outdoors. It will get absorbed through the leaves. You could use the spray a few weeks before bringing your plants in and they should be safe to come back in the house.

Since you have fungus gnats, you must be keeping your plants too wet. Cut way back on your watering and only water when dry. You should not have those gnats. They only survive in moist, decaying matter.

Jane

I can't help re: gnats, but I had a pretty severe mealy problem on about 10-12 phals a couple of years ago -- similarly lost control quickly using the Qtip/alcohol method. I mixed up a 50/50 solution of isopropyl alcohol & water in a spray bottle, and thoroughly spritzed the orchids. They hide everywhere -- underneath pots and even on the surfaces where pots sit (window ledges, table top, etc.). Check diligently for new mealies every day, and isolate the affected plants. It took several months, but I finally managed to get rid of them. Good luck.

Dawn or ivory about 1/2 ounce to the gallon. Excellent contact killer. Other dish soap could be bad as it has degreasers. If they are hiding and a systemic is needed use Orthene. Better than Bayer because Bayer has multiple chemicals in it. I like to use the least amount and avoid other solutions for other bugs when not needed. I add Orthene to my fertilizer but will use it alone if I do not want to wait on the timing of my feeding.

For an addition to everything listed above with fungus gnats, set out a small dish with apple cider vinegar, a drop of dishwashing liquid, and a few drops of water. Kind of swirl it together, then set it on the table next to the worst affected plants. Cover it 98% of the way with a paper towel, but allowing a small entrance. The gnats love to hide and some (not all) will go under the towel to get the vinegar. Then the dishwashing liquid mixed in keeps the gnats from leaving (they sink).

The OP is going to bring her plants inside for winter. Orthene should not be used in a closed environment such as a house. Best to try to take care of the insects before you bring them in.

I used the Bayer product as a last resort when all else failed. I did not use it inside the house but would use it outside prior to bringing them in. I would use the granular release over winter inside with caution and isolate the plants.

Wish we would hear from more Northern growers to get safer ideas.

Jane

Northern grower here...

I use Bayer Rose and Flower 3 in 1 (concentrated liquid for disease, pests and fertilizer) and/or Malathion for mealies, I very occasionally use Avid for spider mites (be very careful with Avid). For the last 2 weeks I've been treating all outside orchids with either a spray and/or heavy watering with the Bayers. After three successive weeks of treatments, I'll feel safe in bringing them indoors for the winter, which will be sometime next week here in Ohio. If I have any critter issues over winter, I'll take them to the garage for a quick spray or dunk and then back to grow room. Luckily, I can close doors and crack windows in my grow room if things need airing out for a few hours.

The fungas gnats are usually drawn to broken down media, the above treatments will eliminate them, but you need to find the broken down media and replace for a long term solution.

FWIW: As an winter indoor grower with limited grow space and crowded plants, I haven't had much luck in controlling any infestation with a soap/neem mixture, 'big guns' for me have worked.

Good luck,

Bob

2 ways to get the bugs. Contact or systemic. I've given up on contact poisons as non degreaser dish soap kills on contact also. About 1/2 oz to the gallon. My big gun is Orthene that kills on contact and is a systemic. Yes, be careful with Avid. It can harm your plants. and the damn spider mites need to use varied poisons because they get use to the poison. And dish soap kills them best anyway. And they don't get use to it.

Thank you all for your suggestions..... We have no pets/kids in the house and would rely on Avid/Merit but orchids absorb stuff so slowly and we won't use it on our edible fruits plants - only the hibiscus where it does a wonderful job of controlling aphids and I guess mealybugs 'cause we have not seen any. Also good for scale. Trying to control fungus gnats with a top coat of builder's sand - as they were recently repotted in Moisture control soil mixed with sand and packaged orchid bark. We probably have a tendency to overwater - especially if we are away for a week..... Going to spray the trees with Insecticidal soap and then Neem oil X2 before bringing them in.... Plan on repotting orchids into clean pots with new moss or appropriate mixtures and dunking plants into the soap solution - roots and all. Will post pix when the forest comes into the house! Thanks.

Buy a package of "Mosquito dunks" at the garden center. Put one
quarter of one in your watering can. This will kill the larvae in the
soil and stop future generations. It is all natural and safe. Use
sticky traps and manually kill the adults.

Hmmm, isn't Imidacloprid one of those poisons (neonicotinoids) that is notoriously killing off honey bees and other pollinators and in fact wreaking havoc on all our insects including those that are beneficial predators?

I am not being judgmental since I used it myself as part of my arsenal -- on orchids I was trying to grow, in point of fact. In fact, I have to admit that it was mealybugs that defeated my efforts, Imidacloprid notwithstanding.

Knowing what I know now, though, I would hesitate to use this poison outdoors -- and even indoors, since it didn't work for me.

Alas, It is depressing to think that there is probably tons of it everywhere, since it is used in extensively in commercial agriculture as a treatment for seeds.

Two years ago I was concerned about it because I saw a bee die after I had used an insecticide on a rose bush for other pests. But this year, we had plenty of bees, so they have bounced back at least in our area. I had stopped, however, spraying outdoor plants with anything that could kill bees. Indoors....it does not matter, just don’t spray around people or animals directly, let it dry. Bugs do not belong indoors anyway. (Well, most people think that, lol).

Buying organic is one way to ensure you aren’t on the receiving end. But I have to say, lots of things I’ve bought that are labeled organic do not taste as good. I haven’t figured out why yet. Maybe it’s grown in different medium, like coconut husk or volcanic something or other. People who lived 1000 years ago are probably laughing at us...”organic? Well everything is organic if you really think about it...and they pay how much for an organic cucumber? Hahahaha”

Thanks to all your suggestions.... I ended up repotting all my orchids and removing the damaged rootlets caused by said gnats.... Dunked entire plants in water with alcohol and a tiny bit of imadocloprid (we don't eat the orchids and they remain indoors). So far so good..... The hibiscus and citrus that were sickly were repotted in their appropriate media, again removing the nasty rootlets, and pruning the plants. Some got 1/4" of builder's sand over the mosquito bits. Lost a few hibiscus and the citrus are slowly recovering in the house (New York winter), but I MAY have seen 1 or 2 gnats since summer!. Mealybugs on orchids controlled as noted above. Whew! BTW, this took 4 entire days!