Cabbage worm myth - debunked!

Such a pretty little butterfly.  Such a destructive little larvae!  Cabbage worms abound on my brassicas this year, so I just purchased a roll of floating row cover.  But it's too late for the ones that are already being munched on.  What to do?  Search the internet, of course!  Hmmm...here's a possible solution: "Simply sprinkle a mixture of flour and baking soda onto the leaves.  Then, when the cabbage worms eat the baking soda, they die."  Sounds easy, right?  Wrong :(

Well, I actually did the sprinkling thing, but I decided to go one step further.  I put 2 large cabbage worms into the leftover baking soda / flour container to see what would happen.  After 2 1/2 days they are still going strong - happily eating all the baking soda / flour they desire.  (I know they are eating, cause I see the poop.)

 

If anybody has actually had luck with this method, please let me know.  Otherwise, I suggest we save our flour and baking soda for the kitchen!

UPDATE:  I washed off the brassicas today and noticed that the flour/baking soda mixture actually bleached out the leaves in some places.