I am having the hardest time eradicating a fungus gnat infestation indoors. I’ve stopped watering, sprayed with Safer’s End All, placed sticky traps and vinegar traps, and still have a problem with several plants. I am certain they came from a bag of soil (MiracleGro) and now I can’t seem to get rid of them. Any advice would be really appreciated!
Thank you for consulting the Toronto Master Gardeners,
Adult fungus gnats are harmless but can be very annoying. You do seem to have tried almost all recommended actions to get rid of them. I suspect perhaps you haven’t given the process enough time to eliminate all existing eggs and larvae.
You will have to have patience because it takes a little time to break the life cycle of these pests. These gnats lay their eggs in soil and under plant debris on top of the soil. The hatched larvae feed on plant debris, become pupae, then adults which fly around ready to mate and keep their families going. Since the larvae can’t survive in dry soil, continue to cut back on your watering. Water only when plant soil is very dry. You could also sprinkle a thin layer of sand on top of the soil to help keep the top dry. Also continue with the sticky tape to catch the pesky flying, crawling adults.
There are several good previous answers on our website. which give you more detailed info on fungus gnats and their control. Click on the link here provided .https://www.torontomastergardeners.ca/ and type in fungus gnats in the search box(to the right) on the Ask a master gardener page. to access this info.