Canna leafrollers can range from a small nuisance to a major destructive pest. Warmer coastal areas of the United States tend to see the most activity of these pesky caterpillars.
There are two different species of leaf rollers, each creating their signature of damage among canna leaves. The common leaf roller (scientific name: Calpodes ethlius) chews at the edge of the leaf and creates a pocket. Handiwork of the lesser canna leafroller (scientific name: Geshna cannalis) creates tubes from unfurled leaves that are tacked shut, keeping the leaves from opening.
Canna leaf roller pocket
Open the pocket created by the common leaf roller to find the culprit.
Leaf roller caterpillar
You can unfurl the stitched leaf tacked together by the lesser canna leaf roller to find further evidence... plenty of worm frass (poop)!
Look closely in the creases of the damaged leaf or among the worm frass and you will find the offender. You may find one or many! This caterpillar can create quite a bit of damage for its small size. Below is an image of the lesser canna leafroller. It is about the size of a fingernail clipping. More information on the life cycle of both caterpillars can be found here.
Now that you have identified the canna leafroller, how do you get rid of it?
There are several options for chemical and organic treatments to help remove this pest from your yard. Removing the caterpillars and squishing them or feeding them to birds is the first line of defense as well as scratching off the eggs from the top or bottom of the leaves.
egg of the larger leaf roller caterpillar
Next, choose an insecticide that you feel most comfortable using. Thuricide (bT) is a naturally occurring bacteria that damages the stomach of leaf-eating caterpillars and insects so that they are unable to continue eating. Thuricide is our recommended product. Stay consistent with weekly applications of Thuricide.
Customers tell us of their success with neem oil recipes and garlic barrier products as well. We recommend Acephate as a last resort effort because of its damage to beneficial insects. Mix 3/4 tablespoon per one gallon of water and apply three times, each with a three-day interval. With any product, be sure to apply the spray into the rolled leaves as well as the underneath side of the leaves.
If you have extensive damage, you may want to cut all of your foliage down to the ground. (You will be surprised at how quickly cannas are back up and blooming!) Do not add your discarded leaves to a compost pile. Throw your affected leaves in the garbage.
Continue to watch for any further damage. An occasional unfurled leaf can be easily taken care of with a big squish!
Winter care is the most important step!
Canna leafrollers overwinter in the dead leaves. When your season ends, be sure to cut all of your foliage down to the ground. Then completely discard it in the trash. This will be after your first frost. For those in areas where your cannas do not get frosted, cut your foliage down at the end of your fall season. This is a huge help in removing leaf rollers from your yard for next summer.
If you live in an area where canna leaf rollers are more prevalent, we recommend beginning applications of insecticide in the spring before you see any evidence of the worm.
If you have any further questions about canna leafrollers, or other ways that we can help you get the most out of your cannas, just let us know. We are always glad to help!