Do you reuse the soil in you flower pots, Clair? Your best defenses are cultural, that is to regularly check your your flower pots, especially during late afternoon and evening when cutworms are more active, so you can detect their activity when they are first present. Also inspect your plants in the morning when damage is fresh and easier to see. Cutworms should curl up into a tight "C" when you touch them. If you must rely on an insecticide, choose one containing carbyl, cyfluthrin or permethrin as the active ingredient.
You sound like you know what you are talking about, Mr. Hunt. My boss had 3 tomato plants that got cut by a cutworm that he never saw, and the other day it cut a cantaloupe vine. My boss is frustrated. He looked on the internet and put part of an empty toilet paper roll around the base of the 3rd tomato plant, but even that didn't work. He did buy an insecticide, but the cutworm got the cantaloupe vine after that! I will check and see if the product he bought has the ingredients you suggest, but is there anything else he can do?
Tell your boss to try an aluminum collar instead of the toilet paper roll, making sure it goes into the soil by a couple of inches as well as above. (And I don't know where you are, but cutworms are usually an issue much earlier in the season, so is your boss sure this is what the problem is?)
Well, he looked up what it could have been, and it definitely looks cut. We are in the desert part of Southern CA, and we hadn't had this problem before. It actually happened on a cantaloupe plant, too. Thank you for the information, Douglas!!
For Garden cutworm collars I take an cut up cottage cheese containers and put them around each plant and it serves as a water reserve too. Just cut out the bottom and put it over the plant.
Add brokened eggshells, epsom salts, and coffee grounds around your soil. Helps the soil, plants, and the worms should not like the salts and broken sharp eggshells.
sprinkle baby powder for cut worms and snails too