Answer: Cannas are largely free of pests but plants sometimes fall victim to the Canna Leaf Roller and the resultant leaf damage can be most distressing.
Slugs and snails are fond of Cannas and can leave large holes in the leaves, preferring the tender young leaves that have not yet unfurled. Red Spider Mite can also be a problem for Cannas grown indoors or during a very hot, long summer outdoors. The Japanese Beetles will also ravage the leaves if left uncontrolled.
Without knowing which of these pests is munching on your canna lilies, I can't really make a recommendation. Once you identify the culprit, your local garden center can help map out a control program.
Best wishes with your garden!
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