Beetle infestation #412688 - Ask Extension

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Beetle infestation #412688

Asked July 08, 2017, 2:03 PM EDT

I have a Calla Lily in my front garden that is probably 4 years old. It is an off-shoot from a much older plant. The problem is, the healthy plant is being destroyed by Japanese Beetles. Is there a way I can treat this plant and not kill bees or other beneficial insects? I am not sure if this needs to be treated systemically. A beetle bag was recommended, but that has done nothing to alleviate the problem. The lily is about 5' high, grows in clay soil and gets morning through afternoon sun. I first noticed the issue on June 24th and have tried to treat with insecticidal soap (which is briefly successful, but more beetles return within 12 hours). Symptoms have continued to progress with each passing day. Any advice would be greatly appreciated.

Baltimore County Maryland

Expert Response

These look like canna lilies, not callas.
They are loved by Japanese beetles, as you are seeing, making a lacy mess of the leaves.
First off, we do NOT recommend a beetle bag. They actually tend to attract more beetles to your yard than you would tend to have naturally.
The good news is it can be controlled organically if you are willing, it just takes some effort.
To do this, go out either in the cool or the morning, or in the evening, with a small container with 2-3 inches of soapy water. Japanese beetles are slower and more sluggish then. When disturbed, they tend to drop straight down, so put the container under them, and gently tip the leaf towards your container. They will fall in and drown. You may find them on roses, Rose of Sharon, cherry and other plants too. Doing this regularly can really make an impact on their numbers.
For the worst leaves (and the spent flower spikes), trim them out to tidy the plant.

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