The larval form are in the soil you must kill them one way or another.... replace soil would be one to achieve this... by transplanting as soon as possibe you will also solve the problem.

I just got word that my containers have shipped, so they should be here soon, and then I can transplant. I may move these babies out in the shade so at least the flies stay outside! Thanks!
Suzi

I googled this question, and found a video that showed me I needed to trap the adults in a mixture of apple cider vinegar, bit of soap and sugar, and sit that near the plants. Done!

Next, scoop out the top half inch of the soil in the container (in my case 120 containers), and replace with good old plain sand. They don't like sand! So I did that also, because it will be a week to two months till they all get planted!

They are now outside in the shade getting hardened off to what lies ahead for them!

I hope this works!

Suzi

The larvae in the soil are eating the new roots. They are easily controlled with BT. Dissolve mosquito dunks or I use granulated mosquito BT which dissolves faster in the water. A couple of applications to the soil and they are gone. Al

BT?
What is that?

Bacillus thuringiensis a bacteria found in many pest controls. Look for mosquito controls and read the label for listed ingredients. Mosquito dunks should be available everywhere. Al

Thanks Al! I'll pick some up today. I worked too hard to get these cuttings to grow and form their little roots, and I don't want to feed gnat larvae!!

Suzi

I feel your pain. I've got some apple tree seedlings and some sun flowers on the window sill and the gnats are driving me crazy. I'm on day two of vacuuming up the adults and watering with the mosquito dunk stuff. They are maddening.

Hey,
I had this same problem in my dormroom. My roommates didn't like it too much. Here are some good solutions using household objects. Furthermore, you can mix a solution of 1 part dish-soap, 3-part listerine, diluted with water in a spray bottle. This will kill emerging larva.

Here is a link that might be useful: Envi Sci and FshyPlnts

It seems they are more attracted to organic cutting mixes that might include peat and they will lay their eggs in that. I dumped the mix I had for my cutting and used straight course vermiculite. It seemed to help. Cuttings will root in the vermiculite, as for continued growth Im not sure.

its much easier to PREVENT THEM .... rather than try to cure them ...

sterilize your media ... per the link ... i dont care what the bag says.. do it just prior to use ...

also sterilize all your pots and implements.. with 10% bleach ....

the drench is not sure fire ... as you kill only those parts in the proper stage ... which means you have the potential for the ones flying around to come back and re-lay eggs ...

sterilize some media.. and repot all your plants .... clean soil is a good start.. then figure out how to kill all the ones flying around.. perhaps move the clean ones to another room.. until the primary room is devoid of gnattal life forms ... [with their short life span ... its not a long wait ...

ken

Here is a link that might be useful: link

On some of my pots I replaced the top inch or so of soil with sand or in my case vermiculite same thing[not course] and it seemed to detour knats. Also I tried the apple cider vinegar didnt work for me. But I found this video on something called sticky stakes which is similar in looks as sticky cards except it has the stakes to put in the soil and anyway I ordered the sticky stakes and should get them this week. Following is a vid of the sticky stakes. I also found these on ebay for $7.85 free shipping.

Here is a link that might be useful: sticky stakes

Steve, I've never found targeting the adults to be that helpful, they only live just a few days anyway and do no damage themselves - other than the egg layings. If you use the BTi - subspecies is important - Bacillus thuringiensis subspecies israelensis - available in Gnatrol, Knock Out Gnats, mosquito dunks, others, and stop the breeding cycle you can eliminate gnats. If you have seedlings trays or cutting flats around and damp, might want to consider just keeping it on hand so you can treat right away. And use it about three consecutive weeks so you know the larvae are gone.

That suggestion about adding sand to the top doesn't work - I've watched the gnats go in and out of drainage holes at the bottom of pots where there is moisture longest.

morz8

Here we go again. Which came first the chicken or the egg. If you can capture enough or maybe all adult gnats who will lay the eggs? But on the other hand gnats seem to get in the house regardless of what you try to do so I also have some systemic granuals which Im going to try as a backup. Altogether this should help.

systemic granules as a back up - a systemic insecticide then? That's overkill for gnat larvae IMO, and your choice of course but I wouldn't use one indoors. I recommend the BTi because 1) it's completely effective, and 2)it isn't going to harm you or pets in any kind of enclosed room or space.

I haven't had more than a temporary, brief problem with the gnats since some kind soul here on GW recommended the BTi to me years ago. I use as needed, more often in flats outdoors than in, and gnats and their larvae just aren't an issue any more....you don't have to continue to deal with them with the right product.

The stuff I used is " bonide systemic granuals insect control" This stuff is great on my indoor cuttings. Used it a few days ago and have not seen that first gnat. I also poured a pan of boiling water down the kitchen drain to kill any stuff breeding in there. Hooray!!