Answer: As if one isn't enough, there are three species of leafrollers and leafeaters that feed on cannas! Try Bacillus thuringiensis var. kurstaki (Bt for short; often sold as Dipel or Thuricide). Bt is a naturally occuring disease organism that makes caterpillars sick when they eat it. It eventually kills them. Watch the plants closely for signs of the caterpillars, and as soon as they appear, spray twice a week until they are gone.
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