Fungus gnats-- was --Looking for pic of the smaller Narcissus fly

Kelly O'Neill
Sun, 29 Mar 2009 19:35:06 PDT
> To clarify, Bacillus thuringiensis israelensis is used against Diptera 
> larvae, most commonly mosquito larvae but also fungus gnat larvae.
> The form which kills caterpillars is different -- it's Bacillus 
> thruingiensis kurstaki.

Jean is correct about the recommended subspecies of BT to use. I looked 
into what seemed to work for me. I seem to have used the "wrong" ones. I 
have used both:

Bonide® Thuricide®
Bacillus thuringiensis variety kurstaki.
Safer Brand Caterpillar Killer With BT - 
Active Ingredient Bacillus Thuringiensis. Var. Kurstaki 

> When mixed into the irrigation water for potted plants, one must 
> continue using it for at least 3 weeks to disrupt the fungus gnat's 
> life cycle.

   The stuff is destroyed by sunlight and the kind I used is supposed to be 
sprayed on the leaves. Thus, reapplication is needed above ground. My gut 
feeling (an inside joke for those who know how Bt works) is that this stuff 
lives longer than a week in the soil if watered in. I will go out on a limb with 
very little (or no) evidence to say I think the stuff is happier in the soil than it 
was in the bottle of concentrate and colonizes a never dry/frozen/extra 
hot/poisoned soil. Whether you reapply or not, it still takes weeks to do the 
  I should try the "right" stuff sometime. I still would not trust the israelensis 
strains (Vectobac, Mosquito Dunks, Gnatrol, Bactimos, etc.) on my butterfly 
larva foliage.

 Kelly O'Neill and 
   Big Bubble Magic(tm) at
and  Wet Rock Gardens Flower Farm
2877 N 19th Street - Springfield, Oregon 97477
U-Pick and more at the farm (open 9 to 6, Sun, 
Wed and Fri - from March thru Halloween) -

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