Why Is My Cactus Attracting Flies?

Cacti are beautiful plants, but sometimes you may see small fruit fly like bugs buzzing around your favorite houseplant. Those flies are called fungal gnats, and they tend to suck out the fluids of the cactus. Thus, the cactus becomes very weak . Since they are rapid breeders, if left unchecked they can become a nuisance very soon.

What attracts the flies towards cactus?

Cacti are generally dry plants, so if over-watered the plant is likely to attract gnats, especially during hot days. If the soil is too moist and the conditions are humid, it provides the ideal breeding grounds for gnats. Cacti are generally most susceptible to gnat infestations when they are seedlings and need moist soil to grow. While the gnats feed on the plant sap, its larvae devour the roots in search of fungus. These flies are highly contagious and can spread fungal infections to other plants when they start to breed and multiply.

How to treat cactus if infested by Gnats?

So, if your cactus is infested by gnats, these are the following steps that you can take to check the infestation –

  • Natural Control
  • Gnat Traps
  • Pesticides
  • Soil Change

Natural Control

The best way to control gnats in your cacti is to use natural predators which prey on these flies. Place a carnivorous plant-like sundew or butterwort with sticky leaves next to your cacti. These plants prey on the flies and help control the nuisance. Another effective remedy is to layer the soil in the container with coarse sand. It prevents the gnats from accessing the moist soil and makes them unable to breed and reproduce.

Gnat Traps

You can also use traps to help reduce the infestation of gnats. Sticky traps which are available in local gardening stores can be used. These are essentially yellow sticky pads that cause the pests to stick on them and eventually die off. Another homemade remedy is to make yellow cardboards and cover them with petroleum jelly, which serves the same purpose as a sticky pad. Similarly, you can also net the cactus to prevent the flies from having access to the plant.


You can also use an effective commercial fly repellent to help keep the flies off your plant. Another method is to spray a diluted solution of hydrogen peroxide on your plant to kill the larvae and check the reproduction of the flies. Natural fly repelling oils, such as neem, can also be used to help keep the flies off your cactus.

Soil Change

If your cactus is infested with gnats, it is most likely that they have already started reproducing. Check your soil and if you see any larvae, immediately re-pot it with sterilized soil. Also, ensure that the new soil is fresh, well-drained, and coarse, to ensure that the flies don’t start to reproduce again.

Thus, these are the steps to help curb the nuisance of gnats in your cactus. However, remember that gnat re-infestations can occur very easily, so you need to be careful about the complete removal of these flies to ensure the safety of your cactus.

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