I don’t know where they came from I don’t know how they keep spreading I keep thinking I get rid of them and they just keep on coming and destroying how do I get rid of these for good
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Are you growing in coco?
I use a Botanical Tonic Bundle Including Sprout, Citrus, Neem & Ritha Tonic, so Neem oil is great for foliar spray and a light topsoil mist which will help but the tonics can be fully watered into the soil. A great combo for gnats would be Neem tonic + Ritha tonic soil drench and a Neem oil / Ritha Tonic foliar spray (the Ritha / soapnut tonic emulsifies the Neem oil making it water soluble).
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Root maggots are the larva of fungus gnats. If you have fungus gnats, then you’ve been watering too much or your medium is holding too much water. Fungus gnats love saturated medium and need it to lay their eggs and thrive.
There are a couple of things you can do to kill fungus gnats and their larva.
Let the top 1"-1.5" of the medium dry out completely between waterings. A fan may be used to help dry out the top layers of the medium. Letting the top layers of the medium dry out will kill fungus gnat eggs and larva… the adults will fly away looking for moist medium to start over in.
DE or Diatomaceous Earth and/or neem may be spread over the top of the medium and watered in. DE and neem are both natural pest control remedies that work on a variety of different insect pests
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Nats are mostly gone I’ve already started to not water as much but even in new clones that I take and in domes they are still there ima try that neem oil And get back to you thanks
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I’m a look into these products you are talking about thanks
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Yeah no problem, here is the website to get what I am talking about. I got the 4oz bundle
I have also had success with Mosquito Dunks or Bits. I put them in a coffee grinder and make them into powder then water them in. They kill larvae of flying insects and are Organic. I have never had to use nematodes but a buddy with a large warehouse grow says they are amazing. You add these to the soil and they kill the larvae (bro science here as in “Bro they kill the babies!”)
Here. Dunks.
And the Nemotodes. This is a Package that has everything you need to wipe out fungus Gnats.
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DE has a lot of Phosphorus, Nitrogen and Potassium, if you put a lot of quantity it is better to water from the bottom so you won’t have a nutrient excess, it is definitely a killer for the bugs … 
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There are these guys, too:
Their product is Bacillus thuringiensis israelensis (Bt-i) as a liquid amendment.
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It’s funny you should ask whether he was growing in coco. My soil mix has both coco and peat to try to be a little more environmentally responsible and it attracts/breeds fungus gnats like crazy! I vacuum them out of my cabinets multiple times a day.
All the suggestions that folks are giving here are great, but you will probably always have a few around. There is a small species of rove beetle that hunts them and really lowers their numbers, but it is hard to keep around indoors. Like @DesertGrown said, the DE spread on the top is great and then to water them from underneath with a wick system. I don’t think it needs to be watered in though, as the DE cuts both the adults emerging from the soil from the pupal stage and the adults returning to lay eggs. The version I used with success is Insectigone by Chemfree.
I have reset things successfully with hydrogen peroxide at a mix of 1-2 TBSP/litre of 3% if you’re growing in soil, but please start light if you do this. It really did work though and dissipates quickly.
I have lost some rarish seedlings from fungus gnat larva because I didn’t sterilize recycled soil. They will eat roots sometimes.
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Yes fungus gnats are present in overly wet media’s but I’ve noticed them the most in coco. I use the microbe lift that Loki mentioned. Two to four drops to a 30 gallon Rez usually does the trick of eliminating them.
Yes another trick you mentioned is to pasteurize the media you plan to grow in.
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I was just reading in a Rodale organic gardening book a solution to all soil-borne larvae, including nematodes. It’s a nuke that kills everything in 10 minutes flat (even worms): sugar water, in enough concentration that the osmotic pressure in the fully saturated media will draw out the moisture of every single larvae within. Ain’t osmosis a bitch? Within 24 hours a heavy watering to flush out the excess sugars is written as “mandatory”, or plants will show signs of stress and crop health declines.
No idea what concentrations are needed for this–it would require further research. I know I’ve seen studies showing 1% molasses in water is a precursor for a bloom of fungal activity and phosphorous availability. But I think this sugar treatment is in excess of 1% concentration. Sounds pretty radical, like it would mess up a healthy soil ecosystem. But I can also see it being a cheap quick surefire way to instantly eradicate these root maggots and whatnot. Especially in a sterile media. If I grew hydroponically I’d try it out myself. All my good containers have living soil going though, some in 3rd year.
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I think when you sterilize or pasteurize a soil you also kill the beneficial microbes needed to absorb the nutrients … 
You can always add the microbes back in.
I use food grade DE when I need to use it… and you’re right George, it has nutrients in it too. The finely ground up diatoms contain approximately 33% silicon, 19% calcium, 5% sodium, 3% magnesium, 2% iron and various trace elements such as boron, manganese, copper, zirconium and titanium to name a few… however there is no nitrogen found in it.
These will be the approximate percentage values found in the amount of DE you use. Wet DE won’t harm insects… it must be dry to do that.
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I have the impression that DE needs to remain dry to be effective.
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You can use DE also as a foliar spray, it will stick to the leaves once the water is evaporated, act against the bugs by contact and protect from sunburn as it reflects the light and prevents heat. If you want to kill the reptants as slugs or insects like ants in the floor, you must put them in their paths and nests, but as AllOra says once wet it is useless and you must renew it …
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This rockstar had white diatomaceous earth coating its leaves for the first two weeks of its life. I was afraid the white would block the light but it did no harm.
My DE rig. $15 bag, I paid extra for food grade. I hear breathing the non can cause lung trouble.
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and buy 25 Kg for almost 20 €, lots of snails and slugs in my garden … 
