Have you noticed your outdoor plants looking especially raggedy, the previously bold, big, rounded leaves now jagged and sickly looking?
It’s frustrating and disappointing when tropical plants such as Cannas suddenly begin looking bad, and it has nothing to do with heat, drought, or your lack of care. Your cannas and other large-leafed plants are instead the victims of Calpodes ethlius and Geshna cannalis, otherwise known as Leafrollers.
Leafrollers are the larvae of butterflies, and they rely on the nutrients from your leaves to make their final transformation. Eventually, they will become brown butterflies, but until then, they can wreak some massive destruction to ornamental plants and some trees, like oak.
They get their names from the way they burrow to protect themselves. Nesting on a healthy leaf that then folds around them, they secure their abode with silk or webs. The best way to determine if you have them is to study your plant for a moment. If you see a leaf folded over about an inch from the edge, pull the fold apart. The larvae will be inside the sticky fold, and the mystery will be solved.
Generally, these larvae go unnoticed, with minimal damage to your flourishing plant. But sometimes – this summer, for instance – there is a particularly large population of them in our area, and they are doing some serious damage.
In my backyard, they have devastated my cannas. What’s even more surreal is that the larvae feed at night, so when I let my dog out before going to bed, I can actually hear them munching away on my leaves. That’s how prolific they are right now and explains why the damage seems to be worse every morning when I step outside.
So what can you do if your plants are infested by Leafrollers? Your first order of business is to remove any leaves that are folded over. This will take some serious inspection and much time and care in pruning. In my case, I have so many damaged leaves that a better option is to cut the plant down and start over. This isn’t as bad as it sounds since Cannas grow quickly, but it’s frustrating, especially when you’ve waited for full growth to replace what you lost in the spring freeze.
If you’re torn over how to handle your plants, consider the life cycle of the Leafrollers. They will create more than three generations per year. They lay anywhere from 50 to 300 eggs in late May to early June. The larvae develops over the summer and frantically eat leaves to mature and lay another round of eggs in late August. So yes, the next generation is already deposited on your plants, where they will overwinter into spring, hatch, and begin the cycle again.
Aside from cutting your plants back or meticulously removing infected leaves, you can also purchase Bacillus Thuringiensis, commonly known as Bt, which is an effective organic insecticide. If you’ve tried this product and it doesn’t seem to be helping, experts suggest Neem Oil as another option.
Or, you may decide to let nature take its course and just enjoy the butterflies.