Question
Currently I turned a tote container into a bog garden to be outside. I live in Southern California.  I have fungus gnats in my peat moss.  Right now I am using the sticky cards to catch the adults, but it is also robbing my other plants of flies.  I don't really want to use spray, I have done some research on organic  methods, one being the hypoaspis miles, but there are other bugs and parasites that can be used.  I was wondering which creature or parasite would you recommend?

Answer
It's very unusual for an outdoor bog garden to have a fungus gnat infestation.  This usually happens in greenhouses or indoor growing.   But because it is happening, I'm suspecting that there may be an issue with your setup.  Without knowing the details, I can't comment on what to do differently or what factors might be contributing to the issue.  Or there could be nothing wrong with the setup.  I just can't rule it out at this time because an infestation of fungus gnats in outdoor containers is almost never a problem.

There are several organic solutions to taking care of pests.  First is pyrethrin, which you can purchase at your local garden center.  It's rated for organic growing because it's derived from a plant.  The same is true for Neem oil.  You may need to apply weekly until the infestation is eradicated.

As for beneficial insects, I'm not aware of any that attack fungus gnats and their larvae specifically.  However, you could try BotaniGard.  It's a predatory fungus that is safe to use on plants, but is deadly to insects.  I'm not sure how well it will work on fungus gnat larvae, but it should work well on the adults.  It will, however, attack other insects, good and bad.  Generally this is used in a greenhouse setting.

Another option is using mosquito dunks.  They contain a bacteria that specifically attacks mosquito and fungus gnat larvae.  It's safe on other forms of insects, amphibians, mammals, and birds.   It's also safe on plants.  We use it here during the summer time.  You can break up the dunk and sprinkle it over the soil surface.  You'll then need to top water regularly regularly to allow the bacterial spores to enter the soil.  You can find mosquito dunks online or at your local garden center.


Good growing!
Jacob Farin