fungus gnats

gnats don't hurt anything. Some say the larvae from their eggs don't do damage.

I have evidence the larvae are extremely damaging to Haworthia (ornamental succulents) under certain conditions.

Any ideas how to deal with them. I use Dawn biodegradable with every fogging and work diligently to control harmful insects without toxins.

We are at limit though. Last year we had a lot of spiders helping us. For some reason they have not been so helpful this year..the gnats go all winter..

Any ideas will be welcomed.

I'm sure somebody has dealt with these little critters.

Cheers!
bob
thistleisfter :>)

I don't know who told you the larvae don't do damage but they definitely do, they can nibble at the roots of the plants. The adults don't harm plants (except indirectly since they're responsible for the larvae!) The first thing I would do is check your watering. I've never had trouble with fungus gnats except when I was overwatering something, and if you've got them in your Haworthia the excess moisture that led them to breed there will likely kill your plant long before the gnat larvae will do significant damage. You can use yellow sticky traps to catch the adults, and Bt (Bacillus thuringiensis...purchase as Gnatrol or mosquito dunks) to deal with the larvae. There are other techniques too--if you search around here a bit you should find several threads talking about them--I think some of them are in the seed germination & propagation forums since that's an area where people commonly run into trouble with them.

Hi Bob

I grow plants indoor that attract fungus gnats, and I have found several ways to deal with, from the completely organic to the chemical.

I take my Tidal Wave petunias indoors and put them in the windows. Fungus gnats are attracted to them, land on them, stick to the leaves and die. I have a double cascade petunia in the basement I use the same way. You don't need the flowers. The leaves are sticky. Just rinse them off periodically and them put them back to work. This method alone reduces them by 80%.

Insecticidal soap works too, which you can duplicate with dishwashing detergent and preferably filtered water, but it only kills the ones you hit. So as long as there are two, you will get more, but it will take them a while to build up.

The chemical solution is acephate, which zaps chewing insects (but not pollinators) and works on thrips, fungus gnats, spider mites and aphids, in my experince. It is short acting. You can find it in Orthene or Ortho Systemic Insect Killer.

I use all three methods. Based on what you say, and with the concern with larvae, the systemic is probably your best solution.

Donna

Hi ecrane3,Haven't lost plants directly due to water. So watering habit is not in question. I'm happy with that, plants have never looked better . Sorry about your problems with over watering causing fungus gnats. The plants are reacting positively to fogging in my greenhouses. If plants were having difficulty with my watering habits I would have been asking about that. My trouble as I stated, is with fungus gnat larvae!

fungus gnat larvae appear to dig in just below the area where the older,often desecated, leaves or leaf stubs are attached to the stem and where the caudices often form, in the older 10+ year old mature plants where there is caudex material that doesn't have much life. In the only two examples where plants was depleted from the damage these larvae were found to be hidden by shallow borings into that live material closest to the caudex. it appears that they sapped the plant without leaving evidence of chewing on any fresh root or leaf life that can be easily detected. I've not ever found any in the roots.

I will try insecticidal soap.

Thank you both for the comments.

Thistlesifter
Bob

I'm not completely convinced the things boring into your stems are fungus gnat larvae--the gnat larvae would typically live down in the soil and damage the roots. That plus the fact that you're positive you're watering properly (and these plants are succulents which would want to be on the drier side to be happy) suggests to me it might be something else.

((((please help me)))))) get them gone.there killing my christmas cactus cutting and start plants

If you read the earlier posts in this thread, there were a number of suggestions on how to get rid of them--I would recommend trying some of those ideas.

ecrane,i am trying water the plants at the bottom of the pot.am spray pure hydrgen peroxide on the plants and fly trap hanging up.but i need to now HOW at get the bug out of the around the root of my plants?

From my first post:

Beneficial nematodes eat the larvae, and yellow sticky traps catch the adults. Works for me every winter.

will the hydrogen peroxide is working for me .now what???? the yellow fly tape is working on the adults.now need the eggs gone.

Orthene is not exclusive. It kills all, even the pollinators.

I believe that Dori's issue was indoor plants, which would not affect pollinators. I use it in APRIL, before pollinators arrive in MY zone. Your issues, in a warmer zone, are not the same as those of us further north. It is also biodegradable and doesn't build up in the soil or accumulate in the natural food chain. We each need to make educated choices about what we use, where we use it and when.

Donna

yes my issue is indoor plant?all my christmas cactus plants.

Sorry, Donna, for the misunderstanding. I was referring to another of your posts that indicated that pollinators were not affected by the use of acephate. They are. In Texas, Illinois and New York, too.

Which is not at all relevant to the situation at hand. A cold climate indoor growing person wants something effective. This is. I was trying to address a solution that would be effective.

I consider box quoting things from other threads to be impolite. People change their minds about things. A particular individual (whom I'll spare) started a thread praising products that the person has completely disavowed. If you go to the top of that thread you could box comments that would make the person uncomfortable.

You would be right, but would it be appropriate?

I quoted this from THIS thread! I did NOT quote from another thread. I have not been impolite. Nor inappropriate. Just correcting an error. I wouldn't want anyone to think that using an insecticide is not going to kill pollinators.

You're the one that is making a big deal out of this!

Whatever.

Now, now. Play nicely, kids.

That said . . . .

I have house plants and not a whole greenhouse. I have used Neem Oil, even double and trible solution which is now killing my plants.

I am confused, what product do I need?

Your problem may be that you're not doing anything about the larvae in the soil--unless you do something to deal with them you're going to continue to have problems. There have been a few suggestions earlier in the thread about how to deal with the larvae--I'd try some of those. Also watch your watering--fungus gnats are much happier when you're watering a bit too much. And for the adults, if you're not having luck with neem then I'd try the yellow sticky traps or insecticidal soap instead.

I have been spraying the soil with Neem Oil.

I have looked on the Internet and found some products including the sticky traps. Now I am off to see if I can find any of these in the stores!

One thing I found was that if you lay 1/4" slice/wedge of potato, the larvae will be attracted to it. Then check in a few days. I probably have all of them, eggs, larvae, and adults for sure.

One person said that if you put lemon and lemongrass essential oil around the innner edge of the pot, it will kill them. I am trying Pledge for now. lol

As ecrane said "You can use yellow sticky traps to catch the adults, and Bt (Bacillus thuringiensis...purchase as Gnatrol or mosquito dunks) to deal with the larvae.

That's all you need. It doesn't harm the plants and the Gnatrol or mosquito dunks kill the larvae in the soil. They are watered into the soil, not sprayed on the leaves. They work. They don't stink, and they don't have a wide spectrum kill. Bt is organic, too - if that is a concern. They are used for the larval stage of insects such as mosquitoes and fungus gnats. Kill the larvae and you don't have adults flying around.

Have you used the mosquito dunks? They seem like they are to be used in standing water. There are 4 of the donuts in a package. I have 54 plants so I would have to cut those into pieces even if I bought 3 packages. It seems like I would have to use a lot of water to water them in. And cutting them up would put some of that powder in the air which is not good for asthema. Plus they don't look very aesthetic pleasing.

I bought those tapes but I surely am not hanging them from the ceiling. I will have to try to cut off little pieces. I don't know if that would work because they are so sticky.

I bought a spray with pyrithrine (sp) in it so that should work better.

Also, I got some fine peat moss. So I will take out about 1' soil from each pot and replace it with the peat. They say that helps.

Garden guy suggested Seven that we use for those Japanese beetles here. I think that would be too strong for inside but will check out the label. I always have some of that.

I couldn't find any of those other products.

I really had great results when I used beneficial nematodes and yellow sticky traps together.

http://naturescontrol.com/flea.html

This message was edited Feb 26, 2010 6:50 PM

You could put the nematodes in your house plants? Even the 4-6" pots?

They didn't have yellow sticky traps so I got the tape. So what are the traps like? Maybe I can make my own.

Yes, I have used the mosquito dunks. I break them up, with my fingers, and then place a few small pieces in the watering can with water. Let them sit a bit (they won't dissolve as such) and then water.
If that sounds unpleasant to you, you could use the gnatrol, http://www.planetnatural.com/site/gnatrol.html which is liquid, diluted with water, and watered in.
I don't personally use the sticky traps, which are to catch the flying gnats, because there are none once the larvae are killed.

I put the nematodes in every pot I had. They destroyed the gnat larvae and any other pests in the soil.

The sticky traps are kinda like stiff, skinny Post-It notes with a pointy end that you stick into the potting soil. They're ridiculously gluey on one side, and the yellow color is specifically chosen to appeal to the adult gnats. They like that exact wavelength of yellow.

I looked up Gnatrol and at the bottom of their info, it said that it is no longer being manufactured. Just as well. That sure is a large container. Would take me many years to use all of it! lol

Before I start using nematodes or other things, I will use what I bought today. And I will try to make my own gnat traps. If you don't hear from me again, I am all tangled up in those long sticky strips!!! LOL

Venice62, do you have "Safer" products in your garden centers? They have one called "Caterpillar killer" that is a liquid form of bacillus thuringiensis. It doesn't have instructions for a drench, but it should work. The Dunks take a while to disolve.

Yes, I bought a Safer product today. I don't remember seeing Caterpillar Killer but I wasn't looking for it either. It sounds good. I will see what I can do in this next week. If these darn gnats are not gone, I will try some of that. Thanks.

Unfortunately, the Bt that kills caterpillars is a different strain - kurstaki. It isn't effective on fly larvae. I had no idea that gnatrol was no longer being made. Durn! What you need is Bti - or Bacillus thuringiensis israelensis. That is what Mosquito Dunks are made of. Here is more information on the two strains.
http://www.ext.colostate.edu/pubs/Insect/05556.html
I need to do some more research to see what has replaced Gnatrol.

I made a mistake. I thought I bought a Safer product but it was a Garden Safe one.

Safer and Garden Safe are usually the same ingredients.

ok, thanks!

ceejaytown, excellent info on that link...thank you for straitening me out! It never occurred to me to look at the strain.

You are very welcome. Always glad to help...(and get it too).

I knew I was getting little bites from something. Well, it's the gnats!!!

http://www.islamicity.com/science/quranandscience/animals/generatedfiles/THEGNAT.htm