I don't know how well it would work for what is bothering your plants, but neem oil may help. Use it as a soil drench early in the growing season for the plants to have a systemic effect and use it as a foliar spray when bug populations are increasing.

sounds like leaf rollers.

I left mine alone this year, 'cause I learned that leaf rollers turn into Northern Skipper butterflies, but the cannas look *so* awful that I don't think I'll do that again! (and I only saw maybe 2 butterflies.)

BT, or bacillus therengensis (sp?), will kill leaf rollers as well as other caterpillars, & trichogramma (s?) wasps will kill them before they hatch.

Trichogrammas are tiny microscopic wasps, not the big kind that sting.

Best luck and enjoy your flowers!