Gnatrol Bti for Fungus Gnats

My indoor gardens got a Fungus Gnat Attack, and the gnats were everywhere!  I don't know where they came from, but apparently I brought something into the house that had them, and they quickly multiplied.  I first noticed them several weeks ago when I was harvesting lettuce for dinner - as I was disturbing the soil pulling the leaves off the lettuce, the Fungus Gnats started flying everywhere.  Since the larva stage of the gnat feeds on the roots, I had to get rid of them.  All of my garden seedlings had those gnats flying around them, too.

I ordered some Gnattrol Bti (Bacillus thuringiensis, subsp. israelensis) from gnatrol.com, and started applying it to the soil of all plants, including the houseplants, following their 15-day schedule (apply every 5 days for 3 times to break the gnat's cycle).  After the 2nd application, I noticed fewer gnats, but there were still some around. When it came time for the 3rd application, there were very few gnats flying around, but I still made sure to make the 3rd application.  It has now been a week since the last application and there are no gnats to be seen, but just to make sure (OCD?), I made another application of the Bti to the soil of all of the plants.

All in all, the investment in the Gnatrol seems like it was a worthwhile investment for controlling this pesky gnat.

Each year, fungus gnats appear in my yard.  Would regular bT work?

OG,  Thank you for posting your experience with this product.

Reading some articles seems to indicate that different subspecies are more effective on different larva. I'm getting some kind of fly or gnat, dark with silvery looking wings. They are crawling around on the ground.

Yes, Sanderson, there are many different subspecies of Bacillus thuringiensis (Bt). Gnatrol is Bt-i, which controls only fungus gnat, Black Fly, and mosquito larva.
Bt-k is for tent caterpillars, gypsy moth, cabbage looper, tomato hornworm and other leaf eating caterpillars. Bt-sd and Bt-t are for the leaf-eating Colorado potato beetle. Milky Spore Disease is Bt popillae, and affects the Japanese Beetle grub. A relative new one introduced is a product called GubHalt, which is Bt galleriae which affects all white grubs, including the Japanese Beetle grub.

There are probably other Bt as well, but these are the ones I am familiar with.

Thank you.

, OG. I thought these guys were just annoying. I had no idea they were killing my plants.

CN, they are annoyingly eating the roots of the plants, especially the tender new hair roots.

Has anyone tried "sticky cards" or "mosquito dunks"? I'm gonna try DE one more time, first.

https://www.almanac.com/pest/fungus-gnats#RID

OhioGardener wrote:My indoor gardens got a Fungus Gnat Attack, and the gnats were everywhere!  I don't know where they came from, but apparently I brought something into the house that had them, and they quickly multiplied.  I first noticed them several weeks ago when I was harvesting lettuce for dinner - as I was disturbing the soil pulling the leaves off the lettuce, the Fungus Gnats started flying everywhere.  Since the larva stage of the gnat feeds on the roots, I had to get rid of them.  All of my garden seedlings had those gnats flying around them, too.

I ordered some Gnattrol Bti (Bacillus thuringiensis, subsp. israelensis) from gnatrol.com, and started applying it to the soil of all plants, including the houseplants, following their 15-day schedule (apply every 5 days for 3 times to break the gnat's cycle).  After the 2nd application, I noticed fewer gnats, but there were still some around. When it came time for the 3rd application, there were very few gnats flying around, but I still made sure to make the 3rd application.  It has now been a week since the last application and there are no gnats to be seen, but just to make sure (OCD?), I made another application of the Bti to the soil of all of the plants.

All in all, the investment in the Gnatrol seems like it was a worthwhile investment for controlling this pesky gnat.

OG. I've tried everything else and failed. I'm placing my order for Gnatrol right now. 

Mixed 1 gal. Organic BTI. Only used half. Should I keep using until its gone or refrigerate until time for next treatment? I posted this on their site, but I think they're back east and already closed for the day. Any suggestions?

PS -- While looking for my answer, I found out that this stuff also kill mosquito larva, but won't harm plants or beneficial insects.

Here's their prompt reply to my email:

Gnatrol wrote:Once you mix it up it is only going to be effective for about 3 days so try to only make enough for each watering.

I'm in the middle of my 3rd treatment. I've noticed a slight improvement, but that's all.

Today, I was treating my kale for aphids, with the free sample of Dr. Zymes I got last summer, and discovered it will also kill fungus gnats, so, if Gnatrol doesn't work, I'll try Eliminator next. (The flyer says it also works on mildew, which would be really nice. )