Pest Severity: High ⚠️ Contagious

Caterpillars: Urgent! How to Save Your Plant

Caterpillars are the larval stage of moths and butterflies that feed voraciously on plant foliage, stems, flowers, and fruits. Common species include cabbage loopers, tomato hornworms, armyworms, and cutworms. These pests can cause extensive damage by consuming large amounts of plant tissue in a short time. They vary in size from small (1/4 inch) to large (5 inches), with colors ranging from green to brown, often featuring stripes or spots. Caterpillars are highly mobile and can quickly spread throughout gardens, making them one of the most destructive common pests.

Spread speed

Fast

Recovery time

21 days

🔍 Symptoms

Main Symptoms

! Irregular holes and ragged edges on leaves
! Large portions of foliage completely consumed
! Dark cylindrical droppings (frass) on leaves and soil
! Visible caterpillars of various sizes on plant surfaces
! Skeletonized leaves with only veins remaining
! Bore holes in fruits, vegetables, and flowers
! Defoliation starting from leaf edges
! Stunted plant growth from severe feeding damage
! Presence of white cocoons or pupae on plants

Visual Signs

Irregular holes and notches chewed in leavesLarge portions of leaves completely consumedDark droppings (frass) visible on leavesVisible caterpillars on plant surfacesDefoliation and skeletonized leavesBore holes in fruits and vegetables

Affected parts: LEAVESStemFruitsFlowers

❓ Possible Causes

→ Adult moths and butterflies laying eggs on host plants
→ Eggs hatching into hungry larvae seeking food
→ Warm weather accelerating reproduction cycles
→ Poor garden sanitation harboring overwintering pupae
→ Lack of natural predators in garden ecosystem
→ Dense plantings making detection difficult
→ Introduction from infected transplants
→ Nearby weeds serving as alternative host plants

💊 Treatment

⚡

Quick Fixes

~11 days

Step 1

Hand-pick all visible caterpillars immediately and destroy in soapy water

Step 2

Mix emergency spray: 2 tablespoons dish soap + 1 quart water

Step 3

Add 1 teaspoon cayenne pepper or hot sauce to soap solution for added deterrent

Step 4

Spray solution directly on caterpillars and all leaf surfaces

Step 5

Use strong water spray from hose to physically dislodge caterpillars

Step 6

Remove severely damaged leaves and plant parts to eliminate hiding spots

Step 7

Repeat soap spray treatment every 2-3 days for one week

Step 8

Monitor plants twice daily and remove any new caterpillars immediately

Materials needed:

Pyrethroid insecticide (deltamethrin)CarbarylChlorpyrifosConcentrated Bacillus thuringiensisPressure sprayerGloves and mask

🌿

Organic Treatment

~21 days

Step 1

Inspect plants early morning or dusk when caterpillars are most active and visible

Step 2

Hand-pick caterpillars wearing gloves, placing them in jar of soapy water

Step 3

Check leaf undersides and stems for eggs (small clusters of white or yellow spheres) and crush them

Step 4

Mix Bacillus thuringiensis (Bt): 1-2 tablespoons per gallon of water in spray bottle

Step 5

Spray Bt solution thoroughly on all foliage, especially leaf undersides where caterpillars hide

Step 6

Apply Bt in late afternoon/evening when caterpillars are actively feeding for best results

Step 7

Reapply Bt every 5-7 days or immediately after rainfall

Step 8

Introduce beneficial insects: release ladybugs (1,500 per 1,000 sq ft), lacewings, or parasitic wasps

Step 9

Encourage natural predators by planting nectar-rich flowers (yarrow, dill, fennel) nearby

Step 10

Install bird feeders and water sources to attract insect-eating birds

Step 11

Apply diatomaceous earth around plant bases as physical barrier

Step 12

Continue monitoring and hand-picking for 3-4 weeks until no new caterpillars appear

Materials needed:

Bacillus thuringiensis (Bt)Neem oilSpinosadPotassium soapPheromone trapsParasitoid wasps (Trichogramma)GlovesSpray bottle

🔬

Expert Treatment

~32 days

Step 1

Identify caterpillar species using field guide or extension service for targeted treatment

Step 2

Document infestation severity: count caterpillars per plant, photograph damage

Step 3

Hand-pick and destroy all visible caterpillars and egg masses

Step 4

Apply professional-grade Bt (Bacillus thuringiensis var. kurstaki) at labeled rate

Step 5

Supplement with spinosad-based insecticide (organic option) if Bt alone is insufficient

Step 6

Deploy pheromone traps to monitor adult moth activity and predict egg-laying cycles

Step 7

Install floating row covers over crops to physically exclude adult moths

Step 8

Release commercially-reared parasitic wasps (Trichogramma) timed to egg-laying period

Step 9

Apply neem oil (azadirachtin) to disrupt molting and feeding behavior

Step 10

Implement trap cropping: plant sacrificial host plants away from main crops

Step 11

Use selective fast-acting insecticides (e.g., spinosad, indoxacarb) only for severe outbreaks

Step 12

Rotate insecticide modes of action to prevent resistance development

Step 13

Monitor weekly with systematic plant inspections and sticky traps

Step 14

Practice fall garden cleanup: remove plant debris, till soil to expose pupae

Step 15

Document treatment results and adjust integrated pest management (IPM) strategy

Step by Step

1
Identify caterpillar species if possible to target treatment
2
Hand-pick all visible caterpillars and drop into soapy water
3
Remove heavily damaged leaves and destroyed plant parts
4
Apply Bt (Bacillus thuringiensis) spray thoroughly to all foliage
5
Reapply Bt every 5-7 days or after rain for 3-4 weeks
6
Introduce or attract beneficial predators to garden
7
Monitor plants daily for new caterpillar activity
8
Use physical barriers like row covers to prevent reinfection
9
Continue monitoring for 2 weeks after last caterpillar sighting

🧪 Solutions

🌱 Natural Solutions

✓ Hand-pick caterpillars daily in early morning or dusk when most active
✓ Apply Bacillus thuringiensis (Bt) spray targeting young caterpillars
✓ Use insecticidal soap on small caterpillars and eggs
✓ Spray neem oil to disrupt feeding and growth cycles
✓ Release beneficial insects: ladybugs, lacewings, parasitic wasps, tachinid flies
✓ Encourage natural predators: birds, ground beetles, assassin bugs
✓ Apply diatomaceous earth around plant bases as barrier
✓ Use spinosad (organic bacterial insecticide) for severe infestations
✓ Deploy pheromone traps to monitor and reduce adult moth populations
✓ Apply garlic or hot pepper spray as natural feeding deterrent

💉 Chemical Solutions

✓ Fast-acting synthetic pyrethroids for immediate knockdown
✓ Carbaryl (Sevin) for broad-spectrum caterpillar control
✓ Permethrin or bifenthrin for persistent protection
✓ Systemic insecticides containing spinosad or chlorantraniliprole
✓ Follow label instructions carefully for application timing and rates
✓ Rotate chemical classes to prevent resistance development
✓ Apply in evening to minimize harm to beneficial pollinators

🛡️ Prevention

✓ Inspect plants regularly, especially leaf undersides, for eggs and young larvae
✓ Remove eggs and small caterpillars by hand before populations explode
✓ Use floating row covers to exclude adult moths from laying eggs
✓ Maintain diverse plantings to attract beneficial predators
✓ Plant aromatic herbs (rosemary, sage, thyme) as companion plants to repel moths
✓ Keep garden free of plant debris and weeds that harbor pupae
✓ Rotate crop locations annually to break pest cycles
✓ Encourage birds by providing water sources and nesting sites
✓ Till soil in fall to expose overwintering pupae to predators and cold

🌿 Common in These Plants

Delta Maidenhair Fern

African Milk Tree

Moon Orchid