Houseplants, Cactus

To all plant lovers,

who can help me?

My beautiful cactus is blooming again—what a joy! That makes these little flies all the more annoying.
I’ve already had to throw away one plant because it got really bad.
A colleague of mine said they’re so-called... gnats. I don’t remember the name, but they lay their eggs in the potting soil, and now the little critters are buzzing all over the living room.

What can I do about this? Especially now that it’s blooming.
Thanks

Those are fungus gnats, Andrea. Try using matches—stick the heads into the soil. The sulfur is supposed to repel the gnats.
Sprinkling a layer of quartz sand (1–2 cm thick) on top of the potting soil might also help. Coffee grounds work as an alternative.
You can also buy yellow sticky traps at garden supply stores.

After it finishes blooming, I’d remove all the soil and replant the cactus.

Best regards
Marlies

Those yellow sticky traps may look silly, but they’re actually quite effective at first. But after it finishes blooming, I’d also replace all the potting soil and replant it.

Using less water should also help—those gnats need moist soil.

If you add new soil, make sure it’s gnat-free. It happened to me after repotting—they just showed up, practically a free bonus.

I’ll try the coffee trick. Then I’ll try the matches.

Thanks for the tips 

Thank you so much for your tips.👏

I’ve heard about the matches before—I’ve already tried that. Let’s see what happens.
Okay, then I’ll just wait until the blooming period is over. I’ll try coffee grounds, too.

Wow, those are great tips! Thanks!

Andrea, let us know what works. I’d be interested in that, too.

Andrea, just make sure your coffee grounds don’t get moldy! You can also heat the new potting soil in the microwave for 2 minutes beforehand—that will kill any fungus gnat eggs and larvae that might be there.

Thanks, Mel. I’ve done some research in the meantime—I’ve also read about killing them in the microwave or in the oven.
I won’t use coffee grounds, though—you’re right, they can get moldy, and then even more flies/fungus gnats will show up.
I just picked up these yellow sticky traps at dm. We’ll see how it goes. Two of those little beasts are already stuck to them. (Within just one day so far.)

I’ll keep you posted.