Gnats around my Phal.

[Anne H.]

My Phal. looks healthy with new leaves and growth, but recently I have noticed a couple of gnats flying around the pot. Evidently, the gnats are living in my phal. pot. They must be attracted to the moisture. Does anyone know any pesticides or remedies that I can use to kill the gnats and not hurt the orchid? Should I repot the orchid?

[Tobi]

Anne,
Fungal gnats are more of a nuisance that causing any real problems to your
orchid. They are attracted to damp and decaying bark. If your potting media
is old, then repotting will help control them somewhat. I have used a mild dish
washing detergent in my watering. A couple of applications when you water
has temporarily gotten rid of them for me. Good air circulation also helps.
Cynthia has also recommended mosquito dunks which you can buy at a
garden center to control them.

[jbigio]

Many assume they are fungus gnats which they often are but I have recently also learned that the male mealy bug is also a small flying gnat type insect that fly’s around the plants. I’ve had gnats a few times and have tried several ways to get rid of them. What I have found that works great is a small dish of apple cider vinegar on each shelf. You won’t believe the results.

[Cynthia, Prescott, AZ]

There is a lot of question about the shelf life of the mosquito dunks. I have used one recently that was purchased last Feb. It is not as effective as I recall. Since this is not mosquito season, I would question the freshness of the dunks. Also, we had such an incredibly bad case in one very large pot, let it go too long, that we needed results now. So, out came the ready mixed pyrethrin spray that I keep around for all kinds of problems. Used to use it for keeping the slugs off of my flowers when I had a bad infestation in the GH. A very light dusting did that job, so I have used the pyrethrin spray, very lightly on the surface of the pot, because I don't want to kill too many of the organisms from the mosquito dunks within the pot. This seems to be really working well, so long as I spray the pot tops about a week or a week and a half apart.

When I was using it on the slugs, I felt that $4 a bottle was too much, so I bit the bullet and bought a quart of concentrate for about a hundred dollars. I am now making up my own bottles, reused from previous purchases, at about a $1 a piece. Comes in handy when the termites swarm just after the monsoons start and invade our bedroom and living room. Finally, after 5 years, found out they were coming down the fireplace flues, even with the dampers closed. I went up onto the roof in the middle of the swarm and sprayed the chimney, and that turned them off like a switch. In the mean time, it takes an hour a piece of spraying and vacuuming to clean up the two rooms. Fortunately, it was only the bedroom this last time. We now have lids on the fireplace chimneys that will have to be removed before we use the fireplaces.

[robb]

I had some gnats in a few of my non-orchid houseplants, and found some yellow sticky papers worked great. I think it's basically a sheet of glue-paper on a stick, but the colour is what attracts the gnats. As they hatch and fly up, they are attracted to the brightness of the paper, effectively ending the life-cycle.

[tom499]

Sticky sweet liquids in pot saucers are a great way to kill alot of flying bugs Natural and safe, and cheap to maintain.

I'd also recommend a sundew or pinguicula, both love eating gnats and other bugs

[Cynthia, Prescott, AZ]

I also noted that there are a lot of gnat like things milling around between my piñon pine and my front door. Seems they must like the piñon pine, as I saw a lot randomly distributed around it. I'm wondering if the left over gnats in the house are coming in from outside. I expect this to stop real quick as the weather is going real cold now. So in the future, I can probably be pretty sure they are coming from my house plant pots.

[Anne H.]

Thanks for all of the great advice! I really appreciate all of your answers. You're all so helpful!