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

Charles Hesselein chessele at acenet.auburn.edu
Thu Apr 18 07:49:21 EST 1996

In <316feba2.1428324 at news.islandnet.com> annie at islandnet.com (Annie Pang) writes:

>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)

Dear Annie,

Better be careful with your Raid spray.  Avoid using any sprays which 
have synthetic pyrethroids as active ingrediants.  These pesticides are 
extremely long lasting and toxic to predatory mites.

*    Charles P. (Chazz) Hesselein         *
*    Extension Horticulturist, ACES       *
*    chesssele at acenet.auburn.edu          *
*    1-334-342-2366  fax: 1-334-342-1022  *

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