If you are transplanting, you can prevent cutworm damage by simply placing a small stick )or even a tiny stone, if your soil has them) directly against the stem of the plant while planting. The stick or stone should be partly above and partly below the soil line.Wow... I have never heard of rodents chewing tomato seedlings. We have a perpetual rat problem here, but the tomato problems don't start until there is actually ripe fruit; the rats otherwise leave the tomato plants alone. (We are building some serious critter cages this year to keep the rats out.)
But this discussion of cutworms reminds me to be sure to turn the soil over well in the beds that I am currently working on (yes, I know, late planting). The first bed that I worked on had a lot of cutworms in it! So thanks!
Cutworms must wrap themselves completely around the tender stem of the plant in order to sever it. Thecstick or stone prevents that. And it takes a lot less time and fussing than little cardboard collars.
Summerthyme