The cabbage moth begins to appear in spring and summer, increasing drastically in numbers by early autumn. They are white, with a black dot on each wing, and are commonly mistaken as a white butterfly. Though charming to look at as they drunkenly flutter about the garden, these creatures can be a menace. Try watching these moths as they go about their work. Every time they land on a plant, they lay a tiny, pale egg. It only takes a second. These eggs are attached, usually, to the underside of a leaf. When the larvae hatch (tiny, bright green caterpillars), they feast on the foliage, leaving it laced with holes. These moths love cabbages, kales, and broccoli, but will set eggs on other plants, too.
A conventional method for combating these moths is an insect disease-causing bacterium called Bacillus Thuringiensis or Bt. Only by ingesting the bacterium can insects be affected, so, when applied, it’s mostly taking care of the larvae but not the adult moth. Some other natural cures are diatomaceous earth, neem oil, and soap sprays. However, the success rate can vary, depending on how well you can apply the deterrents to the underside of leaves.
Unfortunately, what is effective against moth caterpillars is also effective against butterfly caterpillars. So if you don’t want to give butterflies the boot, try some of these less aggressive tactics. Plant some plants that repel moths: hyssop, mint, peppermint, rosemary, sage and savory. Use a screen or a mesh cloth to cover plants and prevent moths from landing. Give a kid a net and a nickel for every moth they catch. Another trick that I recently learned about, and would like to experiment with, is adding mobile reflective light to the garden. You can do this by hanging bits of reflective metal, like cut aluminum containers or soda cans, that can be turned or spun in a breeze. The reflective light supposedly confuses the moths. Don’t be surprised if you see this experiment happening when we set out our cool season veggie starts.
Creating a healthy and diverse ecosystem in your garden and landscaping also helps combat any kind of pest. Think about creating habitats in your garden that attract bats, birds, frogs, lizards and other insect predators. They will help clean up garden pests like the cabbage moths and their eggs.