Venus fly trap to help with gnat problem?
- Thread starter Mo(no e)
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waterdawg
Well-Known Member
I had them so bad that they would crawl out by the hundreds when I watered. No one at that time suggested the dunk and I tried sharp sand, sticky tape, h2o2, and even raid once when I got really pissed of lol. Good luck! And as rob said, never notice any huge damage but plants may have done much better without them.
Nullis
Moderator
They can be detrimental to seedlings and young clones (if severe enough). For more mature plants they are generally just a nuisance.
Starving your plants of water is likely to do more harm than good, while perhaps affecting the fungus gnats marginally. Plants need moisture too, though; there should always be some level of moisture in your soil/mix. I'm not even sure how anyone could even water properly if they are always letting their potting mix get bone dry before they do water. It's fairly well established that potting mix\soil materials tend to exhibit hydrophobia upon drying out, meaning it will actually repel water at first.
Ever do or witness this experiment as a kid? You take a moist sponge, and a dry sponge and submerge each in a separate bowl of water for a bit to allow them to absorb as much as they can. Then you wring both out in separate receptacles to measure and compare the volume of water absorbed by each. Low and behold, the moist sponge absorbs more water than the dry sponge (keywords: cohesion, adhesion).
Same idea with soil\potting mix; existing moisture facilitates watering and allows the mix to hold more water.
Then of course a potting soil/mix has/should have decent organic matter content: sphagnum, coir even by themselves, earthworm castings, compost, humus, etc. It's all decaying organic matter, and that is primarily what fungus gnat larvae and pupae eat!
These are the stages of the fungus gnat life cycle (which takes about 3 or 4 weeks): eggs--> larvae--> pupae--> adults. Adults do not eat very much and only live for about a week. You really want to go after the eggs, or the larval\pupal stages as well as the flying adults. Bti/Mosquito Dunks do this very well, and it is narrow-spectrum, generally non-toxic to people and pets (still shouldn't be ingested).
Starving your plants of water is likely to do more harm than good, while perhaps affecting the fungus gnats marginally. Plants need moisture too, though; there should always be some level of moisture in your soil/mix. I'm not even sure how anyone could even water properly if they are always letting their potting mix get bone dry before they do water. It's fairly well established that potting mix\soil materials tend to exhibit hydrophobia upon drying out, meaning it will actually repel water at first.
Ever do or witness this experiment as a kid? You take a moist sponge, and a dry sponge and submerge each in a separate bowl of water for a bit to allow them to absorb as much as they can. Then you wring both out in separate receptacles to measure and compare the volume of water absorbed by each. Low and behold, the moist sponge absorbs more water than the dry sponge (keywords: cohesion, adhesion).
Same idea with soil\potting mix; existing moisture facilitates watering and allows the mix to hold more water.
Then of course a potting soil/mix has/should have decent organic matter content: sphagnum, coir even by themselves, earthworm castings, compost, humus, etc. It's all decaying organic matter, and that is primarily what fungus gnat larvae and pupae eat!
These are the stages of the fungus gnat life cycle (which takes about 3 or 4 weeks): eggs--> larvae--> pupae--> adults. Adults do not eat very much and only live for about a week. You really want to go after the eggs, or the larval\pupal stages as well as the flying adults. Bti/Mosquito Dunks do this very well, and it is narrow-spectrum, generally non-toxic to people and pets (still shouldn't be ingested).
Mo(no e)
Member
Oh man, Nullis, you're super helpful, thanks! Since posting this I've put up sticky traps, but haven't seen a single gnat, on the paper, plants or dirt-anywhere. I dunno if I just didn't have an infestation, or scared 'em all off with the readiness to wage all out war, but either way I'm happy they're gone, and to have all this information for future grows! Thanks again, everyone!
Mo(no e)
Member
Oh no, sorry to hear about ripped leaves. And the sand option was the very first tip I found when initially researching the issue, but it seems the plant would be hard to water?
sunny747
Well-Known Member
Naaaa.. it's not too bad to water. As long as you have enough room in your pots it's fine. Over time my soil compacted so I had an inch at the top of extra room. You could always scoop out some soil. I swear by the sand.. They were destroying both of my plants. The spray I bought killed the gnats, but then in a few days more hatched. I have not seen a single one since I added sand. The sand dries out quickly which kills the larvae.
It takes a few seconds longer to water since the sand is compacted a bit, but all in all it works great.. The gnat traps worked alright. Just need to have enough space in grow are so that leaves don't run into them. Sand still works better though.
rob333
Well-Known Member
yeah dont do sand got root rot from that way i look at it if there more then 50 u have a problem i complete grows all the time with a few flying around but soon that top layer of soil drys out there pretty much fucked to be doulbley shore just run bit of peroxcide to kill larva but to be honest they have done fuck all and if u have more then 50 in there and there chewing ur plants to peaces well u have 1 dirty grow room 
2 things i use bit of soapy water i see em i spray em also i line my grow room floor with surface spray be4 every grow they land on it there fucked i have more probems with fucken cat hair more then i do with gnats lol
2 things i use bit of soapy water i see em i spray em also i line my grow room floor with surface spray be4 every grow they land on it there fucked i have more probems with fucken cat hair more then i do with gnats lol
Mo(no e)
Member
Yeah, the fan is a really good idea, i've seen it suggested a few times. And I didn't even think of root rot from the sand on top. And don't worry, i've seen no where near 50! I'd just give up if I did; only ever two or three, and I didn't see larvae when I put the potato slice down. I still haven't seen any, so I think my problems are over. I started the flip cycle today, and am excited to see my plants bush out and be real happy soon. 
thank you everyone for the help!
thank you everyone for the help!
Nullis
Moderator
There is a certain kind of sand that you really don't want to use, I think it might be play sand or construction sand but I am not sure...
I would recommend a Bti product even just for prevention purposes, it works best before an infestation. If you only see a few now would be a great time to use it.
Infestation means a shit-load of gnats, like say a Sticky-Stake or yellow fly strip catching at least dozens of gnats in under a week. Then you might need to start vacuuming them up periodically; use pyrethrin spray on the soil surface and Bti for the larval stages.
Maybe cedar mulch would be a good repellent. There is also that other light aggregate product that kind of looks like gray perlite.
I would recommend a Bti product even just for prevention purposes, it works best before an infestation. If you only see a few now would be a great time to use it.
Infestation means a shit-load of gnats, like say a Sticky-Stake or yellow fly strip catching at least dozens of gnats in under a week. Then you might need to start vacuuming them up periodically; use pyrethrin spray on the soil surface and Bti for the larval stages.
Maybe cedar mulch would be a good repellent. There is also that other light aggregate product that kind of looks like gray perlite.