basic question on Bt

Anne Kilmer viceroy at
Wed Jul 8 14:57:26 EDT 1998

Liz Day wrote:
> Hi...
> Is all Bt used for insect control the same?  I mean does any kind of Bt
> kill any kind of caterpillar, or is it more complicated than that?  I have
> wondered this for years, and of course the garden centers have no clue.
> They also sell Bt for mosquito larvae, and I wonder if that can effect
> leps too.
> Somebody please enlighten me.....
> Thanks.
> Liz Day
> LDAY at
> Indianapolis, Indiana, central USA - 40 N latitude, zone 5.
> Where the &^$%@! promie larvae are all cocoons now as it's 90F every day.

Ah, the cares of moth-erhood. 

About Bt ... Chris Conlan keeps explaining it so nicely. Here is a 
simplified version missing most of the good bits.
Bt occurs naturally in the soil, but not in this ghastly concentration. 
Upon application, it is washed away gradually back into the soil. On its 
way, it may ruin several caterpillars who have incautiously nibbled at 
leaves strewn with it, or the remains of their kin. If the caterpillars 
have achieved any sense at all (3rd instar or so), they don't keep 
eating on it. If they do, they die.
Target bugs need to be willing to sit around on leaves eating them up. 
They can't be hiding inside of branches or water lily stems or squash 
stems because the stuff won't get in there and find them. 

The Bt designed for mosquitoes, Chris assures me, only kills Diptera. 
I am afraid to look this up, as I am afraid that a lot of my small 
friends fall under that heading. Midges, for instance. "Blind 

The Bt designed to kill beetles gives me the cold grues. If I understand 
correctly, it will attack any old beetle, if added to his food. I hope 
the food needs to be living plants. 

The Bt gene-spliced into plants is creating a race of superbugs that 
don't care how much Bt you sprinkle around. None of these is a bug 
you're likely to love and cherish, but eventually they will be the bugs 
we've got. What I find especially scary about this is that the family of 
plants they have chosen to diddle with is the nightshades, which are 
already about as toxic as anybody needs to be. And then we will eat the 
tomatoes, potatoes and so forth. 
I will admit that there are already too many people anyway ... 
Organic veggie growers would do well to strike up alliance with 
bug-collecting children, to their mutual satisfaction. Or raise 
chickens. Or both. 
Anne Kilmer
South Florida

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