Plant Doctor Archive

Bugs on my Cannas

What kind of bugs could be eating my canna lilies and how do I get rid of the problem? They are completly eating away the leaves.

Without actually seeing your plants it is difficult to say what is eating the leaves of your canna lilies. There are three likely culprits — slugs, snails or caterpillars. Slugs and snails like to hide in moist places during the day, and if you carefully examine around the bases of your plants, you might find them there. Caterpillars are more likely to be hidden under the leaves of your plants. They could be camouflaged green or brown, and may be hidden under a webbing of silk. There should also be evidence in the form of caterpillar poo.

Getting rid of the problem depends on your situation. If you have young children or pets (especially dogs) you need to be careful with the use of slug and snail bait. You can either put the bait into an open container that is hard for a child or dog to get into, or buy some snail bait which is non-toxic to pets. If you are very patient, you could remove the slugs or snails by hand and leave them in the open for the birds to eat. The caterpillars could also be removed by hand, but this in practice may be hard to do. You could buy one of the garden sprays available at garden centres or something like Derris dust. Remember to read the label and take appropriate precautions.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

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