Controlling Cabbage Moths
There are a number of ways to control the white cabbage butterfly and the subsequent caterpillars. This nasty pest will affect cabbages, cauliflower, broccoli and bok choy and if not controlled it will destroy your crop. Some of the ways you can control these nasty white butterflies include putting up physical barriers, using cultural control, biological control and non toxic spray.
- physical barriers
- cultural control
- biological control
- non toxic sprays
Before you plant out your seedlings make sure that you check each one over carefully for eggs and baby caterpillars. If you catch these pests before you plant out your garden you are one step ahead. Don't think that because they came from a nursery or garden store that they are necessarily free of pests and diseases.
Place a physical barrier over each seedling – you can buy a mesh basket from a bargain store or individual net pots from a hydroponics store – it doesn't matter what you use as long as the sun can shine on your plant but the holes are too small for the cabbage moth to enter and land on your seedling. There is also an added benefit that the birds which like to feast on juicy young seedlings will also be kept away from your baby vegetables. Alternatively you can use a mesh to cover your entire garden bed and protect all of the plants rather than protecting them as individuals.
If you plant out your garden in a checkerboard style you may be able to thwart the cabbage moth. A cabbage moth must land twice in a row on cruciferious plants (cabbage, broccoli, cauliflower etc) to be effective.
If you plant out other plants of similar height but of a different family you may be able to prevent the moth from getting those essential two landings and means that the moth cannot lay an egg at that time. Not an invincible control measure, but every action helps.
Biological Control – Also Known As Natural Predators
Make sure that the area surrounding your vegetable patch and even within your vegetable patch is attractive to natural predators. They will eat the caterpillars, which in turn will reduce the number of adult moths and eggs. Some of the natural predators you may wish to attract are small insect eating birds. Make sure that there are safe nesting sites and that you have a constant supply of water. Native, prickly shrubs provide both protection against predators for the birds and safe nesting spots. Making sure that there are plants which attract the natural predators of the cabbage moth and its caterpillars. Some of these assassins include wasps, assassin bugs, tachinid flies, ladybirds, trichogramma wasps and wasp larvae. Some of these will eat the moths, some will eat the moth eggs and the most gruesome of all, the wasp larvae will parasite the caterpillar and eat the non essential parts until it pupates and finishes the caterpillar off.
Non toxic sprays
A highly effective biological control against caterpillars is Dipel. It is a poison which affects the stomach of most species of caterpillars and works by being ingested by the caterpillars after it has been sprayed onto the leaves. Within three to five days the caterpillar dies. The active ingredient which kills the caterpillars is Bt, and it is broken down by sunlight so every 5-7 days a repeat application may be required to keep the caterpillars under control.