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HELP! Gnats in houseplants/soil taking over!!!!!!

Annie Pang annie at islandnet.com
Sat Apr 13 16:43:29 EST 1996

On Fri, 12 Apr 1996 03:32:23 GMT, dennis_goos at mindlink.net (dennis
goos) wrote:

>maarten.vanhelden at medew.ento.wau.nl (Maarten van Helden) wrote:
>>They are indeed fungus gnats. They normally feed on decaying matter and 
> I have fungus gnats ,not very severe, in the greenhouse. I am  using "Oasis"
>-florist foam - as a rooting media and have a few -approximately 120 trays- of
>peat moss filled plugs in the same ghse for Gaultheria seedlings.  The gnats
>live in the peat moss I assume, but the flies also swarm all over the foam at
>times and I presume they are living in it as well. Do you think they can live in
>the artificial media and feed only on the rooting cuttings ?
>(Dennis & Mally) dennis_goos at mindlink.net
Hi  Dennis,

I'm in a mild zone 8 in Canada and my "greenhouse" is actually my
basement where I have two climate zones set up artificially.  One is
tropical and is heated and humidified  to 70%.  This is the room I
have the most trouble with as Fungus Gnats thrive in moist warm
conditions.  I am also using a soilless mixture (ph balanced peat,
washed sand & perlite)  and I have been told numerous contradictory
things.  Some "experts"  up here claim that the gnats are harmless to
healthy plants while others claim that they lay their eggs in the soil
and the larvae feed on the organic material.  

I thought that eliminating soil from my mixture would get rid of
them.....actually that is what I was told.  But it didn't.  I tried a
powder type insecticide which was alot of work and seemed to work for
a while but then they were back again.  The bright yellow sticky
strips do catch some but are not too effective  if you have alot of

My next attempt will be to get some special mites from our garden
centre  that apparently eat the larvae in the pots,  containers etc.
They burrow into the soil and establish a sort of eco-system.  It is
most effective if you don't have a bad infestation so I will spray
with indoor Raid first to kill the adults and then wait one week
before putting in the mites.  Apparently you can get these for outdoor
use too ( a different insect )  but I am not going to bother.

Please say hi to Mally for me and tell her I will email her soon.  

Annie (and plants)

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