My Garden

Fungus gnats!

Last post 07-11-2009 4:43 PM by larunlady. 12 replies.

• 05/11/2009 04:10 PM
  larunlady Location: N.E. England Joined on: 05 Nov 2009 Posts: 7	Reply | Contact I am having a real problem with these pests (scarid flies). I tried Provado vine weevil killer but doesn't seem to have worked. Also, they are in my chilli pepper plants, in pots, and it can't be used on edible crops. Does anyone have an idea what I could use? I've tried keeping the pots dry etc. but they are infesting the house!

• 05/11/2009 04:36 PM

  In reply to

  NickR Location: Harrow, Middlesex Joined on: 05 Oct 2009 Posts: 26

  Reply | Contact Hello, I know how annoying these little flies can be!! Earlier this year I re-potted one of our houseplants, using houseplant compost, and within a week or so every plant in the room had these little flies in the compost! When you water the plant they fly around the pot, and you can see them running around on the surface! They don't damage plants as far as I know which is a good thing I guess, but they are a pest. In the end I re-potted all of my plants in new compost (not the initial housplant compost where these little pests must have come from!), and I haven't seen any since. I'm not too sure of any insecticides which are ok for edible crops, but apparently you can catch the adult flies on sticky yellow fly traps. It's also recommended to water the houseplants from below rather than from above as this can help prevent them for coming back in future, although I still water most plants (except my Saintpaulia) from above, and have no more scarid flies. I hope this helps a little, Nick :D

• 05/11/2009 05:33 PM	In reply to
  larunlady Location: N.E. England Joined on: 05 Nov 2009 Posts: 7	Reply | Contact  Thank for that NickR, I have heard watering from the bottom is best. Maybe the only thing to do is as you did, repot the whole lot! I dread the thought - I have dozens of them!  I read somewhere that the grubs do eat the roots but I must say I have never noticed any weakening of affected plants. Not like vine weevils, but that's a whole new story!

• 05/11/2009 09:28 PM	In reply to
  jon jon Location: stratford on avon Joined on: 18 Sep 2009 Posts: 7	Reply | Contact spray with bug killer similar product to vine weevil killer .think it contains sunflower oil, i"ve used it succesfully to get ridof scariad fly& white fly  jon

• 06/11/2009 10:46 AM

  In reply to

  NickR Location: Harrow, Middlesex Joined on: 05 Oct 2009 Posts: 26

  Reply | Contact I've done a little more research on scarid flies, and according to one of my RHS books it also suggests, as a way of biological control, to introduce predatory mites called Hypoaspis miles. I have no experience of using these as a way of control, but I guess if the RHS are suggesting it then it must be tried and tested. You may have to do some more research on these predatory mites to find out more about them, and where you can get them too.  You were right, they can damage plants, but apparently they mainly attack the roots on young plants/seedlings, but I think heathly, established plants should be ok though. It also suggests to make sure any dead matter (leaves and flowers) is removed from the soil surface as they provide shelter for the scarid flies and their larvae. Regards, Nick

• 06/11/2009 04:04 PM	In reply to
  larunlady Location: N.E. England Joined on: 05 Nov 2009 Posts: 7	Reply | Contact  Did you use it as a soil drench? I think this is what I need to get rid of the grubs. Is is Provado bug killer?

• 06/11/2009 04:07 PM	In reply to
  larunlady Location: N.E. England Joined on: 05 Nov 2009 Posts: 7	Reply | Contact  Thanks for that NickR, I will do a search for those mites. Wonder if a certain temperature has to be reached first. Although for the plants in the house that would not be a problem. It's wonderful  how they keep discovering predatory mites and other biological controls for pests. It will probably be the norm in the future as more and more harmful chemicals are withdrawn.

• 06/11/2009 04:22 PM

  In reply to

  NickR Location: Harrow, Middlesex Joined on: 05 Oct 2009 Posts: 26

  Reply | Contact You're welcome :) Yes I think there may be a minimum temperature at which these predatory mites will be able to breed faster than the scarid flies, and hence be able to control them, but I'm not too sure what this temperature is, but as you say I think as they are houseplants it should be easy enough to attain the correct temperature. Believe it or not after me saying I had no more scarid flies, which I haven't for about 6 months, I spotted one on one of my houseplants today!!! I spoke too soon! Well so far I've only seen the one, but now I'll be on the look out for more!

• 06/11/2009 04:48 PM	In reply to
  larunlady Location: N.E. England Joined on: 05 Nov 2009 Posts: 7	Reply | Contact  Ha! Where there is one, there will be a partner and then....I will let you know where to buy those predatory mites!

• 06/11/2009 05:21 PM	In reply to
  bogweevil Location: Joined on: 02 Mar 2004 Posts: 2,043	Reply | Contact http://www.defenders.co.uk/pest-solutions/biological-sciarid-fly-control.html    Boggy Beware the bat-eared bogweevil

• 06/11/2009 05:39 PM	In reply to
  larunlady Location: N.E. England Joined on: 05 Nov 2009 Posts: 7	Reply | Contact  Thank you for that Boggy. Short but sweet! Have put that link in my bookmarks and am sure other people will find it interesting. Having recently used Provado vine weevil killer I have emailed them to ask how long I must wait before using the mites.

• 07/11/2009 04:03 PM	In reply to
  NickR Location: Harrow, Middlesex Joined on: 05 Oct 2009 Posts: 26	Reply | Contact Hehe its ironic isn't it?! Well I'm not quite worried enough to get those predatory mites just yet, I can handle just the one scarid fly and even its little friends, its already been squished and haven't seen anymore :-)

• 07/11/2009 04:43 PM	In reply to
  larunlady Location: N.E. England Joined on: 05 Nov 2009 Posts: 7	Reply | Contact They are quite expensive but I will probably invest in them I think. I hope your squishing is successful!