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#234062 Reply

E. Vinje
Keymaster

Hi Steve –

The best product for tomato hornworms is Bacillus thuringiensis, var. kurstaki, or Bt-k for short. Bt-k is most effective when applied to caterpillars during their 1st and 2nd instars, when they are still small. It must be ingested by the insect, as it is a stomach toxin. Harmless to humans, animals and beneficial insects. Here’s a couple of links that should help.

Good luck!