How to Control Caterpillars Naturally

Are you in a constant battle with caterpillars in your garden and seeking natural ways to control them?

While it’s important to remember that not all caterpillars should be treated as pests (a healthy garden should welcome some locally endemic butterflies or moths), there are times when caterpillar populations need to be managed.

In this article, we’ll explore the Integrated Pest Management (IPM) approach to control caterpillars, a superior alternative to traditional and often harmful “spray and pray” methods.

The Integrated Pest Management Approach: An Overview

The traditional “spray and pray” method of pest control can lead gardeners into a downward spiral, negatively affecting soil health, plant vitality, and overall ecological well-being.

This approach relies on chemicals that not only kill pests but often also beneficial organisms, disrupting the natural balance of your garden’s ecosystem and causing further dependence on those pesticides.

In contrast, the IPM approach offers a more comprehensive and environmentally friendly solution. This method combines genetic, cultural, physical, biological, chemical, and regulatory strategies to manage pests effectively. Depending on the specific pest and circumstances, an IPM plan may use one or more of these methods.

A fundamental aspect of IPM is the regular monitoring of plants. This helps identify a potential caterpillar infestation early, making them easier to manage. Equally important is the correct identification of pests; knowing precisely what you’re dealing with is crucial to choosing the most effective control strategy.

If you’ve identified the culprit for munching on your native grasses as a native butterfly or moth, are you really going to try to eliminate it from the environment?

Genetic Methods: Choosing Caterpillar-Resistant Plants

One effective way to deter caterpillars is by choosing plants that naturally resist them.

Some plants, especially vegetable crops like brassicas, are particularly prone to caterpillar damage in the warmer months. By opting for varieties less appealing to caterpillars, you can reduce the likelihood of infestation.

Of course, just because there’s the potential for pests, that shouldn’t be the end of the discussion as to whether you can plant something or not. If you’re willing to spend the energy on fighting that pest, or you’re happy to accept the damage in stride, go for it.

Cultural Methods: Creating an Unfavourable Environment to Repel Caterpillars

Cultural methods of caterpillar control, such as crop rotation and intercropping, can be highly effective for controlling caterpillars in annual crops. These strategies disrupt the life cycles of pests and reduce their chances of establishing a significant presence in your garden.

Other cultural controls may not directly target caterpillars within an amenity landscape setting but can contribute to a healthier garden that is less vulnerable to pest infestations in general.

For instance, regularly cleaning your garden to remove algae and mould helps prevent a range of pests and diseases. Ensuring plants receive the right amount of water and meet their nutritional needs promotes optimal health, making them more resilient against some pests.

Physical Methods: Direct Action against Caterpillars

Physical methods of caterpillar control are often the first line of defence once you’ve identified a caterpillar pest, and can be extremely effective. Handpicking caterpillars, especially larger species, can significantly reduce their numbers.

This method is most effective in the early morning or late evening when caterpillars are most active.

Barriers and traps can also be used to protect susceptible plants. Sticky traps can capture flying adult moths before they lay eggs, but these are often used as a way to monitor pest populations rather than as a control method. Native reptiles, beneficial insects and even small birds can get stuck to sticky traps.

Biological Methods: Beneficial Insects and Beyond

Nature offers a range of biological controls that can kill caterpillars and help manage their populations. Certain species of parasitic wasps, for example, lay their eggs inside caterpillars.

When the eggs hatch, the larvae consume the caterpillar from the inside. Many birds are also natural predators of caterpillars and can be attracted to your garden with diverse plantings, plenty of habitat and plenty of insects hanging around.

Bacillus thuringiensis (BT) is a naturally occurring soil bacterium that produces proteins toxic to certain pests, including many types of caterpillars. You can purchase BT and apply it to affected plants.

Other beneficial organisms include ladybirds, lacewings, and hoverflies, which prey on caterpillars and other garden pests. These can be attracted to your garden naturally, through dense planting of small flowers like callistemons, westringias and alyssum.

Companies like Bugs for Bugs offer beneficial insects for purchase. When buying these insects, it’s important to release them at the appropriate time for the particular insect when they are less likely to fly away. This may be in the afternoon or at night – check your label for details.

Providing a suitable habitat, such as a garden with a diverse range of plants, will also encourage them to stay. But if you’ve already got the right conditions, chances are they’re already present.

Chemical Methods: Least Harmful Pesticides to Kill Caterpillars

Chemical controls are the last resort in an IPM plan, and even then, the least harmful option should be chosen first. Horticultural oils can be made at home with vegetable oil, detergent and water, and they work great at smothering smooth skinned caterpillars.

If all else fails, you can look into neem oil which has the same properties as a regular horticultural oil, but has the added benefit of being a systemic pesticide as well. From my understanding, it’s less harmful to beneficial insects than another popular “natural” insecticide, pyrethrum.

Avoid systemic pesticides which don’t target a specific type of insect (broad spectrum), which are the most harmful types of pesticides.

Regulatory Methods: Adhering to Biosecurity Regulations

Adherence to biosecurity laws and regulations is crucial in pest management. The recent outbreak of Varroa mite in Australia highlights the importance of strict biosecurity measures, and their adherence by all of us.

Australia was one of the only places in the world where the Varroa mite hadn’t been discovered yet. This mite is a pest for honeybee hives, which, if left unchecked, will cause a hive to overheat, cooking all of the bees and causing a horrific slumping of melting wax.

Unfortunately, some bright spark carried it over here and it made its way through our stringent biosecurity measures. The less this happens, the better.

Companies should also establish their own internal policies and regulations to ensure best practices are followed.

Implementing the Integrated Pest Management Approach: Practical Tips for Naturally Controlling Garden Pests

Implementing an integrated pest management approach involves careful planning and execution.

1.   Regularly monitor your garden for signs of caterpillar activity.

2.   Correctly identify the caterpillar species to determine the most effective control strategies.

3.   Implement physical controls such as handpicking caterpillars and setting up barriers and traps.

4.   Encourage natural predators by providing suitable habitats, and purchase them if necessary.

5.   Use organic pesticides as a last resort, and always choose the least harmful option first.

6.   Follow all relevant biosecurity laws and regulations.

Daniel’s Wrap

Controlling caterpillar pests naturally is possible – you don’t need to reach straight for those chemical pesticides. So, next time you see caterpillars in your garden, remember that you have a range of options at your disposal – from handpicking them off your plants to introducing their natural predators.

Happy gardening!

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