Are All Butterflies and Moths Good for Gardens?
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The Verdict: It depends on the species and life stage. Many adults pollinate or serve as wildlife food, while some caterpillars damage crops. Identify the insect and the actual level of damage before deciding whether control is needed.
Why People Believe This
Butterflies are beautiful, and we have been taught since childhood that they are good for gardens. Moths get a warmer reputation by association. The "save the butterflies" message is everywhere, and it is a worthy cause. But this blanket positive framing ignores the fact that the caterpillar stage of many species can devastate your crops.
What the Research Says
UC IPM describes leaf-feeding caterpillars that may damage garden plants and the predators, parasites, and diseases that naturally suppress them. Cabbageworms, hornworms, and other larvae can be pests on particular crops, but not every caterpillar warrants treatment.
Caterpillar pressure varies by crop, season, and location. UC IPM recommends looking for natural enemies and tolerating damage when practical rather than using an unsupported lifetime egg count to characterize every cabbage white in a garden.
What to Do Instead
Use a suitable row cover before egg-laying begins when physical exclusion fits the crop, and remove or vent it when pollination or heat requires. For existing caterpillars, hand-picking may be enough. UC IPM says Btk must be eaten and is most effective on small, newly hatched caterpillars. If using any pesticide, choose a product labeled for the crop and pest and follow the exact product label for rate, timing, protection, and harvest restrictions.
This week: Inspect the undersides of your brassica leaves for tiny yellow or white eggs and remove any you find before they hatch.
For more on managing garden pests, check out our free Garden Planning Guide at Your Garden Toolkit.
Keep Reading
- Protecting Brassicas From Cabbage Worms
- How to Use Row Covers in Your Garden
- Attracting Beneficial Insects Without Feeding Pests
Frequently Asked Questions
Are butterflies and moths actually harmful in the garden?
The adults are mostly harmless pollinators, but the trouble comes from their caterpillar stage. Larvae of species like the cabbage white, tomato hornworm, and codling moth can do real damage to crops.
What is the most effective way to protect my brassicas?
A properly installed row cover can prevent egg-laying on suitable crops, but no method is universally best. UC IPM recommends identifying the caterpillar and deciding whether damage is intolerable before using insecticides. Match the control to the crop, pest, season, and need for pollination.
Can I support butterflies without sacrificing my vegetables?
Yes. Set aside non-crop areas planted with natives like milkweed and coyote brush so butterflies have habitat, while you protect your vegetable beds with row covers or targeted controls.
