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Indoor plant taken over by tiny flies - help!

#1 · 22nd January 2024, 8:07 pm

i am not green fingered at all!
a friend gave me this plant years ago when it was 10cm or so tall as she said it was un-killable and it turns out to be true. I love it!
Recently re-potted it with compost from the garden centre and now it’s covered in these tiny flies…which now seem to have spread to other indoor plants around the house.
what are they please? And how do I get rid of them? This is only a problem since re-potting…

thanks for any advice!

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#2 · 23rd January 2024, 1:05 pm

Hi @harvies

Thanks for your question about this common pest. These tiny flies on your house plants are known as sciarid flies or fungus gnats. They can be a real pain and cause all sorts of annoyance inside the house. They are harmless to us humans just annoying. They can weaken a plant and cause other insects like white flies to take over as well, so it is best to treat quickly on your money plant (Crassula minor) house plant.

They appear when you use damp compost which hasn't been sterilised, which is usually super rich in organic matter and air. You only need a couple to start laying their eggs in the damp compost, and within a week or two, you end up with thousands of these tiny flies!

The best way to get rid of them is threefold:

1.Sticky fly traps placed in the bottom of house plants containers to catch the adults

2. Horticultural grit on the surface of the soil to prevent them laying eggs

3. Nematode drenches or bacteria tablets that feasts of the eggs.

Usually a combination of the three is needed.

Let us know how you get on!

All the best

Lee Garden Ninja