By Templeton
North Yorkshire,
United Kingdom 
Huge infestation of fungus gnats (at least that is what has been described to me) in and around cuttings and established plants which I brought into a cold greenhouse last Autumn. I hadn't realised that these destructive little beasts could survive over the cold frosty winter months. I have seen one or two of these in the house but thought them to be fruit flies, are they one and the same>? They seem to be difficult to kill off? I also suspect that these may have been introduced within a bag of fresh compost which I had left open after potting cuttings a month ago>?
Perhaps a systemic insecticide may be the best, but grateful for best guidance to get rid of these nasty little creatures.
23 Mar, 2015
Answers
It does seem a problem with compost at the moment I have had the same problem the are definitely coming from the compost.
23 Mar, 2015
Thank you Bloomer, yes I will go and replenish the insect traps but in the meantime I have used a systemic insecticide and at the moment everything seems calm in the greenhouse, however, one of the little *$~#s has just flown past my nose whilst typing this message - nowhere near the greenhouse, I hasten to add !!.
24 Mar, 2015
Thank you Peterathome for your response also. The compost I am sure is to blame and I have sprayed the contents of the bag and sealed the top. Why isn't compost already treated before purchase, I wonder?
24 Mar, 2015
I think mine need replenishing too,Templeton..they look like they have polka dots on them :o) Yours is living life on the edge it seems,having the cheek to fly past you ! It's trying to read what you are typing....a new GOY member??Lol.
24 Mar, 2015
Bloomer - I made sure it didn't make the return journey :-)
27 Mar, 2015
You must have a good aim,Templeton,or just lucky ! :o)
27 Mar, 2015
You could buy a pack of sticky yellow insect traps from a Garden centre,or other garden related stockists,Templeton..they look like plant labels,which you stick in the soil....they work for me..I have had some in my overwintering cuttings in a cold Conservatory all winter,with no problems..more noticable once you have watered the plants..the little blighters fly all over the place,when disturbed,with a 'can't catch me' attitude !
23 Mar, 2015