As I mentioned, Bti is specific to Diptera. Caterpillars belong to Lepidoptra. So Bti won't affect them bu Btk will. Jean in Portland, OR -----Original Message----- From: Kelly O'Neill <email@example.com> To: Pacific Bulb Society <firstname.lastname@example.org> Sent: Sun, 29 Mar 2009 7:35 pm Kelly wrote: ....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.