A: You were visited by hordes of hungry caterpillars. You may well have noticed moths fluttering around the garden – those were the culprits. There’s more than one species that do this!
Fortunately, these caterpillars are easily dealt with. The best solution is to spray the developing cabbage plants with B.t., an organic pesticide that targets caterpillars of all sorts. Don’t wait until you’re already in trouble – either do so preventatively, or at the very first sign of holed leaves. Any caterpillars present will quickly stop eating and die over the course of a few days. The organic solution is simply the best in this case, regardless of your normal maintenance program.
B.t. is a biological pesticide and must be kept from excessively high (or low) temperatures. Buy a fresh bottle yearly and store it in the laundry room or under the kitchen sink.