Caterpillars

Caterpillars may be cute in storybooks, but in the garden, these hungry larvae can cause major destruction in very little time. Whether you’re growing leafy greens, brassicas, fruit trees, or flowers, caterpillars are notorious for chewing through foliage, boring into fruit, and leaving behind frass (droppings) and damaged crops.

This guide will help you identify common garden caterpillars, understand their life cycle, and implement organic, effective strategies for preventing and controlling them.


🧠 What Are Caterpillars?

Caterpillars are the larval stage of butterflies and moths. After hatching from eggs laid by adult insects, they begin feeding almost immediately β€” and aggressively β€” as they grow through multiple instars before pupating and transforming into their adult form.

While some caterpillars eventually become beneficial pollinators (like monarchs), many common types are purely destructive in their larval stage, especially in a vegetable garden.


πŸ› Common Types of Caterpillars in the Garden

CaterpillarWhat It AttacksDescription
Cabbage Worm (Imported Cabbageworm)Cabbage, kale, broccoli, cauliflowerVelvety green body, white butterfly adult
Tomato HornwormTomatoes, eggplants, peppersLarge, green with white stripes and horn at tail end
Cabbage LooperBrassicas, lettuce, spinachGreen, inchworm-style movement, no legs in middle body
ArmywormCorn, grasses, beans, peppersBrown with stripes, often move in groups
CutwormSeedlings of all kindsFat, smooth, grey or brown caterpillars that chew stems at soil level
Corn EarwormCorn, tomatoes, lettuceVariable color, usually found in ears or fruit
Tent CaterpillarFruit trees, ornamental treesSpin silky webs in branches, feed on leaves
Gypsy Moth Larvae (Spongy Moth)Oak, birch, fruit treesHairy caterpillars with blue and red dots

πŸ” Signs of Caterpillar Infestation

  • Holes in leaves (ragged or circular)
  • Skeletonized foliage (only veins remain)
  • Chewed fruit or stems
  • Black or green droppings (frass) on leaves
  • Curling or drooping leaves
  • Webbing or silken tents on trees (from tent caterpillars)
  • Sudden loss of foliage, especially in brassicas

🌱 When Are Caterpillars Most Active?

Caterpillars tend to emerge in late spring and summer after adult moths or butterflies lay their eggs. However, in warmer climates or greenhouses, some species can remain active much longer. Early detection is crucial β€” a few days of feeding can mean total crop loss in severe infestations.


🧰 How to Get Rid of Caterpillars Naturally

Controlling caterpillars organically requires a combination of observation, intervention, and beneficial biology. Below are proven strategies that protect your plants without harming pollinators or the soil.


βœ‹ Hand-Picking

Best for: Small gardens, visible infestations
How to do it:

  • Inspect the undersides of leaves for eggs and larvae.
  • Remove caterpillars by hand and drop into a jar of soapy water.
  • Do this early in the morning or evening when they’re slower and more active on the surface.

🌿 Neem Oil

Best for: General prevention and mild infestations

  • Neem oil disrupts insect feeding and growth hormones.
  • Spray a diluted neem oil solution (follow label instructions) on leaves, undersides, and stems every 7–10 days.
  • Best applied in the early morning or late evening.

Avoid spraying when bees are active.


🦠 BT (Bacillus thuringiensis)

Best for: Caterpillar-specific biological control

  • A naturally occurring soil bacterium that targets only caterpillars.
  • Once ingested, it causes them to stop eating and die within a few days.
  • Safe for humans, pets, pollinators, and other insects.
  • Spray on all leafy surfaces. Reapply after rain or every 7 days during outbreaks.

Especially effective against cabbage loopers, hornworms, and leaf-rolling larvae.


πŸ•·οΈ Introduce Beneficial Insects

Encourage or introduce natural predators that feed on caterpillar eggs and larvae:

BeneficialPreys On
LadybugsCabbage worm eggs, aphids
Lacewing larvaeYoung caterpillars, eggs
Parasitic waspsCabbage worms, tomato hornworms
BirdsMany caterpillar species (install bird feeders)
Tachinid fliesParasitize many moth larvae

Grow flowers like dill, fennel, yarrow, cosmos, and alyssum to attract predatory insects.


πŸ› οΈ Row Covers & Physical Barriers

  • Use floating row covers to block adult moths/butterflies from laying eggs.
  • Remove during flowering to allow pollination.
  • Install collars around seedlings to protect from cutworms.

πŸ”„ Crop Rotation & Sanitation

  • Rotate crops, especially brassicas, to prevent overwintering eggs and larvae from hatching near host plants.
  • Remove plant debris and till soil in fall to disrupt cocoons and pupae.
  • Check surrounding weeds (especially wild mustard, lamb’s quarters) β€” they can harbor caterpillar populations.

🌢️ DIY Caterpillar Repellent Spray

Garlic + Chili Spray

  • Blend 1 head of garlic and 1 hot pepper in water.
  • Let steep 24 hours, then strain.
  • Mix with 1 tablespoon dish soap per quart of water.
  • Spray on infested plants (test on one leaf first).

❗Avoiding Future Caterpillar Problems

  • Start scouting early in spring for moths and butterfly activity.
  • Use decoy plants like nasturtiums to attract caterpillars away from main crops.
  • Practice companion planting with repellent herbs like thyme, mint, basil, and tansy.
  • Keep garden tidy β€” clear weeds, spent crops, and dead leaves.

πŸ§ͺ Companion Plants to Deter Caterpillars

Companion PlantBenefit
ThymeRepels cabbage loopers
DillAttracts predatory wasps
NasturtiumDecoy plant for cabbage worms
BorageDeters tomato hornworms
MintRepels general pests including moths

🌿 Organic Pest Control Summary

MethodEffectivenessUse Case
Hand-pickingβœ…βœ…βœ…Small infestations, visible pests
BT sprayβœ…βœ…βœ…Safe, caterpillar-specific control
Neem oilβœ…βœ…Prevention and young larvae
Row coversβœ…βœ…βœ…Egg prevention
Companion plantingβœ…βœ…Long-term support
Beneficial insectsβœ…βœ…βœ…Biological control
Garlic/pepper sprayβœ…Mild infestations, weekly spray

πŸ› Caterpillar FAQ

Q: Are all caterpillars bad for the garden?
A: No β€” some, like monarch caterpillars, are pollinator species. Identify pests carefully before taking action.

Q: Will BT harm bees?
A: No β€” BT is very specific to caterpillar larvae and will not harm pollinators, birds, or mammals.

Q: What if caterpillars keep coming back every season?
A: Improve soil health, encourage beneficial predators, and rotate crops to break pest cycles.


🧺 Final Thoughts

Caterpillars are one of the most common and destructive pests in the garden β€” but they’re far from unbeatable. With a mix of observation, prevention, and natural interventions, you can protect your plants and harvest without turning to synthetic chemicals. Consistency is key β€” start early, monitor often, and take action before populations explode.