Really irritating little flies

[GeordieVik]

Hi all,

wasn't sure which thread to put this in, as it's houseplant rather than lottie-related.

I seem to have bought some compost that is full of fruit flies (or that sort of size / shape anyway) and the house is infested. OH is threatening to scrap the plants unless I can get rid of the flies - we've stuck up a couple of fly-killer window stickers, but we're still coming downstairs every morning to 5 to 10 drowned flies in the washing up bowl, we share our shower with them, etc...

Has anyone got any suggestions how to get rid of them? Would gravel mulch put them off? Should I buy new compost & repot my plants?

Any ideas appreciated!! Thanks,

Vik

[Alison]

In summer I always have a glass with a couple of inches of red wine vinegar with a little drop of washing up liquid in and then cling film over the top with a few pencil sized holes in it. For some reason the flies are atracted to the vinegar and dive in and drown. Think I saw it on that How Clean is Your House prog and tried it last summer when we had a lot of little flies around the house. Much better than chemicals etc and it works dead well.

[Alice]

Are you sure these flies are coming from your plants. How are they getting to your washbowl and shower. Are the plants in the bathroom or are the flies coming from your drains - drainflies. If you're sure they are coming from the plants then I would just get rid of them. You could change the compost and see how it goes. Good luck.

[GeordieVik]

Alice, they are defo from the plants - if you look carefully, you can see them wandering around in the pots. We have plants in the bathroom & kitchen (diff sorts of plants, only common denominator is the compost I potted them up with!)

Thanks

Vik

[SueA]

Hi Geordievik, they sound as though they could be fungus gnats if they are very tiny black flies. They like damp compost & lay eggs in your plant pots which develop into tiny little creamy/translucent grubs which eat the plants roots. They're not such a problem if the plant is well established but will kill off any seedlings or plants with not much root to start with. I'd repot your plants washing the old compost off the roots & using new compost & try to keep the compost on the dry side so it doesn't attract the flies. They probably didn't come in the compost unless it had been stored somewhere very damp & the bag had lots of airholes in it, but they seem to find thier way into the house by all sorts of methods.

[GeordieVik]

Very useful, thanks Sue - have added potting compost to OH's B&Q shopping list! Do you think once repotted, a gravel mulch would help, or not?

Vik

[SueA]

Yes GeordieVik, I think a gravel mulch would help as they wouldn't be able to lay their eggs on the surface of the compost & also wouldn't be attracted by the smell of damp compost.I'd give it a try.Good luck, hope your infestation disappears!

[GeordieVik]

gravel now added to OH's B&Q list!!

Thanks again Sue - keep your fingers crossed it works!

Vik

[valmarg]

I can't remember the name of the flies, but it is something like scarid. The grubs live in the compost, and you get these horrid little flies hovering about the rooms.

If that is what your infestation is, a watering of your plants with Provado should see them off.

[SueA]

Valmarg, I think that is the proper name for fungus gnats, either scarid or sciarid or similar & I've read that you can treat them with vine weevil killer (Provado or other) as well, wonder how it works though as I thought that was specifically for vine weevils? Not sure if the nematode solution for vine weevils would work also, maybe it would attack the grubs the same way as it attacks the vine weevil grubs?

[srodders]

In my experience Provado (and similar) kill all insect things, that feed on sap or the actual plant matter, as it is a non-selective chemical. However as nematodes are an 'animal' they only attack their host - which depends on what type of nematodes they are

[andrewo]

Leave your compost bins open on a cold night and this should kill them, it is also how you layer the compost that matters, excluding areas for the flies to get in, e.g. you need to cover any material with a green layer, preferably grass and this does help get rid of them.