Fungus Gnats on Cactus Plant – Getting Rid of Larvae, Eggs & Flies

Flying bugs like fungus gnats can make an appearance in or around your cactus plants for several reasons although most tend to do with the soil and how well you maintain it. Here are the steps for quickly getting rid of the tiny flies before the infestation becomes an even bigger problem.

Over-watering your cactus plants

Over-watering tends to be the main culprit for the development of fungus gnat infestations on cactus plants. Fungus gnats and other similar flying bugs love moisture and dampness. Cactus plants don’t require excessive moisture to thrive. You are overwatering your plant if the soil remains super soggy and develops tiny puddles of water. The simplest solution to getting rid of fungus gnats on cactus plants is to reduce the amount of watering. You only need to water the plant when the top layer of the soil looks dry.

If you are using self-watering pots or automated plant watering systems, you may want to re-configure the frequency of watering the device is set to. These devices add a lot of convenience but can introduce fungus gnat problems as they are designed to keep the soil damp at all time.

Gnats thrive in poor-quality soil

Fungus gnats will also appear around cactus plants if the soil quality is poor. You might have brought in cactus plants that have been potted in gnat-infested soil. The existing soil may also not be draining well and this adds to the problem we highlighted on over-watering. If you suspect that the soil is the problem then you will need to repot the cactus plants in high-quality potting mix that drains well and is free of pests.

Using yellow sticky traps

Placing a few yellow sticky traps around the cactus plants may help get rid of adult fungus gnats but they won’t resolve the originating cause of the bug infestation. To completely get rid of the flies around the cactus plants, you need to also eradicate the larvae and eggs in the infested soil.

Repotting, however, isn’t an easy step as household plants like cactus plants can be quite sensitive to a change in environment and may end up going through transplant shock. Instead of repotting, one alternative method to consider is using mosquito bits. Let it soak in the water used for the cactus plants. We would suggest letting the mosquito bits or dunks soak for at least 24 hours in order for this method to be effective.


  • AndLee:

    I think I’ve got some fungus gnats around the house after using Miracle-gro Cactus soil. Anyone had similar experience?

  • Ghost Shades:

    I have these fruit fly-looking bugs around my cactus plants. These plants were given to me few weeks ago. What has everyone found to be the most effective solution to getting rid of these irritating flies???

  • Red Lilac:

    I am seeing some tiny fly-like bugs crawling around the soil of my lovely cactus. Are these fungus gnats as well??

  • Ramsgate:

    Hello, I just found some tiny larvae eating parts of my house cactus (at the base). Couldn’t take photo because it was too blurry. Any tips on getting rid of the larvae without my cactus dying?

  • Maldie:

    Please these bugs are driving me insane. I have bunch of tiny flies around my plant. I tried making soil dry but it didn’t help. What to do??!

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