Fungus gnats can’t get rid off them

[IvoPhal]

So, my anthurium infested all of my orchids collection. I tried neem products, traps, diiatomaceous earth in the moment, all the products available from Amazon de to fight the gnats. My last weapon is potassium soft soap and … imidacloprid.
Any thoughts are welcomed

 

[IvoPhal]

Yep, and beneficial nematodes and bit too.

 

[Ray]

You need a product that contains the bacterium Bacillus thuringiensis.

Many people buy “Mosquito Dunks” or “Bits”, which contain dormant bacteria, and place them in a jug of water. After a few days, there will be enough of a population to allow you to water with the dispersion. Then refill and wait for the next watering. After a few repetitions, they’ll be gone.

I am not that patient, so went with Southern Ag Thuricide BT Caterpillar Control. It has the advantage of being a liquid that contains active bacteria and all of their larvae-toxic secretions, so you just mix it up and apply. It still takes a few waterings to completely eradicate the population as it cycles through its reproductive cycles, but it’s easy to deal with.

 

[IvoPhal]

Thanks a lot, actually I’m using culinex I mentioned above. 1 pill from coulinex is for 20 gallons of water I placed 1 in 1 gallon. Waiting just for 10 min ( time to dissolve effervescent tablet). Instructions are clear water after that and repeat in two weeks. Probably the waiting time is crucial …

 

[mrhappyrotter]

In the USA, we have a product called Mosquito Bits which is a biological control mechanism that uses Bacillus thuringiensis to kill larval mosquitos. This product is also effective against fungus gnat larvae. If you have access to this kind of product in your region, I can elaborate more on how to use it for fungus gnat control (but there's also lots of info online).

Otherwise, pretty much any standard chemical insecticide can be effective, other than those which are purely systemic. Pyrethroids (ex: permethrin) tend to be among the safest around people, but are far from the only options.

For fungus gnat control, contact insecticides will kill adult fungus gnats, but you also need to drench the potting media or at least heavily spray the top of the potting mix thoroughly in order to kill the larvae. You should repeat this treatment at least 3 times, with treatments that are 7 - 10 days apart. You also need to spray all plants in your growing area/house/greenhouse/etc, leave no stone unturned.

From there, if you can access the yellow sticky insect traps (they are bright yellow flat paper or plastic cards with adhesive on them) and monitor those closely. If you see any adult gnats, consider undergoing another round of treatment before the gnats become an infestation.

 

[IvoPhal]

Thank you for your exhaustive answer!.
I try with the safest ones, I have a lot ( left from treating my trees at the village) but give a chance for Bacillus thuringiensis one more time

 

[Ray]

Otherwise, pretty much any standard chemical insecticide can be effective, other than those which are purely systemic. Pyrethroids (ex: permethrin) tend to be among the safest around people, but are far from the only options.

For fungus gnat control, contact insecticides will kill adult fungus gnats, but you also need to drench the potting media or at least heavily spray the top of the potting mix thoroughly in order to kill the larvae. You should repeat this treatment at least 3 times, with treatments that are 7 - 10 days apart. You also need to spray all plants in your growing area/house/greenhouse/etc, leave no stone unturned.

Unfortunately, most insecticides do not affect eggs or larvae in the least. That's why multiple, weekly treatments are recommended, so that the adults - including the newly matured ones - can be killed before they have a chance to reproduce.

 

[paphfreak]

I had a problem with fungus gnats. Then I purchased a couple of Pinguicula's (because they were cool, not for the bugs). After two days they turned black. They were covered with bugs. They pretty much keep my gnats under control. I have also added some droseras. These bug eaters do a bang up job of ants, gnats and other small critters.

 

[My Green Pets]

I got into Pinguicula as well after many recommendations (and some friends sending me some!). They are fun to watch but there will always be gnat survivors. The bacteria, nematode, and chemical routes are the only ways to completely eradicate them.
Of course, every time you get a new plant, you will likely reintroduce a new population.

 

[IvoPhal]

I think this problem is connected with the unusual hot 3 months even at my bonsais covered with spahgnum moss (outdoors) I noticed fungus gnats.
So, to resume : Bacillus thuringiensis left for a couple a days for the larvae and insecticide for flies.
Thank you for your help.
4 ago I had to repot all my collection with indoors plants …..

 

[Ray]

Bacillus thuringiensis left for a couple a days for the larvae and insecticide for flies.

If using the BT treatment, I have found no need to also use an insecticide. With no larvae maturing into adults that can lay eggs, the population quickly dies out. The complete life cycle is only about 2-4 weeks.

 

[IvoPhal]

thank you very much indeed!

 

[Jmoney]

I can vouch for the product Ray mentions; I was up to my neck in fungus gnats thanks to the catasetums that needed heavy watering 2x/week. A couple treatments have really knocked down the population. before treatment it was kamikaze gnats...

 

[kman]

I've found the subspecies israelensis to be the most effective against fungus gnats. Works like a charm.

 

[IvoPhal]

Thank you all, I suppose that Arthurium media,,mostly peat moss is working like magnet for fungus gnats.

 

[Ray]

I've found the subspecies israelensis to be the most effective against fungus gnats. Works like a charm.

Yes, that and v. Kurstaki appear to be effective.