Technically these “worms” are Canna Leaf Rollers and there are actually 2 different types common to the area. The Galveston County Extension website has an excellent write up on these critters CLICK HERE if you want more details. They also present a variety of control/management strategies that can be effective.
This might be the appropriate time for me to describe my overall “philosophy” on pest management. Generally speaking I’m not a big fan of chemical pest control. It’s not that I’m some kind of green, organic, tree hugging, eco-nut - it’s that I’m LAZY. It takes a lot of effort to mix up and apply chemical pesticides and more often than not, they have to be re-applied - more work. Nope, I have more of a survival of the fittest approach. If a plant has repeated issues with a pest(s) and can’t survive on its own, then it probably doesn’t belong in my landscape. I might also add that I’ve worked around pesticides my entire career and I’m aware of the potential health risks associated with long-term exposure. Plus - I don’t like storing these materials around the house. Some of my fellow gardening friends have what amounts to a toxic waste dump in their garage. I shutter to think about the volume of pesticides that contaminated our waters as the result of Ike flooding. That being said - I’m not above spraying if and when necessary. Especially if I can use a material that is low in toxicity or has no chemical toxicity.
Bacillus thuringiensis (Bt) is a bio-control product that is particularly effective on worms and caterpillars. Because it is formulated from a bacterium it is considered extremely eco-friendly. Bt is marketed under a variety of different names but Dipel seems to be the most readily available. Applied as a liquid, leaves should be thoroughly sprayed (especially the undersides) when you see the first signs of munching. Be prepared to re-apply 2-3 times for optimum control.
Spraying plants “before” you have a serious problem is the easy part of this plan. The real issue is what to do about plants that have already been damaged? I cut mine back - severely. Then meticulously cleaned up all the dead leaves and decaying foliage under the plants. That’s where the immatures like to hangout. Then I sprayed the remaining foliage with Bt. I also applied some fertilizer to help get the new growth kicked in to high gear.
Of course there’s a huge hole in the landscape but I guess that’s better than having a bunch of totally munched up plants standing out like a sore thumb. I will keep yall posted on the progress of this pest management project.