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I'm having problems with tiny black flies with my indoor plants. The buggers, also known as Sciarid / Fungus flies, are now buzzing around as I'm typing this.

I've found out that they're attracted to damp compost, and that the maggots cause alot of damage to the tender roots of seedlings (although well established plants should be ok).

Is there a cheap way of eradicating these pests? I've looked around and noticed the high costs of some products, i.e. Gnat off is about £20 per 250ml

Your suggestions please...

I don't know how to eradicate them, but if you always water house plants through the saucer (y'know, pour water into the saucer and allow capillary action to draw it up into the soil) you shouldn't have a problem with these pests.
I would imagine that if you start this now you will reduce the population of the flies within a few weeks...

... another few ideas that are free and won't hurt...

Giving your plants a a luke-warm shower can help blast the blighters away though ultimately you want the soil to dry out well.

You might want to try is getting your house plants out in a breeze on a warm day, I would imagine that would blow lots of them away too. Even getting them on a window ledge by a wide open window, if you don't have outdoor space

And if you notice the beasties on the leaves and stem (like aphids) you could do worse than giving your plants a wipe down with a weak washing-up liquid solution.


HTH

Not an immediate solution - but grow some Dalmatian chrysanthemum (C. cinerariifolium). Let them go to seed (just), pick the heads, dry and pound them, soak 'em for a few hours in a couple of pints of water and then spray the culprits with the liquid. That'll get the buggers. What you'll have made is a completely natural pyrethrum spray, and pyrethrum is bad news for insects. Just be careful where you're spraying it - you don't want to down the friendly beasties.

Mike

There's also a biological control available (Hypoaspis) from all the usual suspects for somewhere just under £15, for enough to treat about 10 square meters.

Good tips here.

I've also found out that putting a layer of dry, sharp sand on the soil stops the flies laying the eggs. To get rid of the larvae under the soil, nematodes (approx £7 per pack) will help. But the downside is cost as they need to be applied every 6-8 wks.

Somebody suggested using neem oil to eradicate both maggots & flies on the soil ; get neem oil solution, put a spoon of it in a jug, add 1 tiny drop of baby shampoo ( not fancy shampoos ) and mix it till white, then add about 50ml of hot water to dissolve it, then dilute with cold water

The sticky traps work very well but the best remedy we have used is to cover the top of the soil/compost in the pot with sharp same or grit and water from the bottom only. It does work.