Caterpillar

Lepidoptera (larvae)

Caterpillars are the larval stage of moths and butterflies (order Lepidoptera). While beautiful as adults, the larval stage is a feeding machine — some species can consume their body weight in plant material daily. Indoors, caterpillars typically arrive as eggs laid on the plant before purchase, or as adults entering through open windows. Outdoors, they are a major defoliation risk on houseplants taken outside in summer.

MonsteraFiddle Leaf FigCalatheaPeace LilyPhilodendron

How to Identify

Irregular holes in leaves, often with ragged edges, and the presence of frass (dark green or brown droppings). Caterpillars range from 5–80 mm depending on species and instar stage. Some are camouflaged and match leaf colour — check leaf undersides and stems. Eggs appear as small clusters of round or oval dots on leaf undersides.

Life Cycle

Eggs are laid in clusters on leaves by adult moths or butterflies. Larvae hatch in 5–14 days and pass through 4–6 instars before pupating. Early instars cause minor damage; final instars are responsible for most feeding damage. Pupation occurs in the soil, leaf litter, or on the plant itself. Adults emerge in 2–4 weeks.

Visual Identification

Leaf Chewing Damage

Mass Defoliation

Caterpillar Variety

Treatment Steps

1
Hand-pick caterpillars and egg masses and dispose of them in sealed bags
2
Apply Bacillus thuringiensis (Bt) var. kurstaki to target larvae — highly effective and safe for beneficial insects
3
Use spinosad-based spray for rapid knockdown of larger larvae
4
Check the substrate surface for pupae — remove any cocoons found
5
Repeat treatment after 7–10 days to catch newly hatched larvae

Prevention

Inspect plants brought in from outdoors carefully before placing indoors
Check leaf undersides for egg masses on new purchases
Use fine insect netting over plants stored outdoors in summer
Remove and dispose of any egg masses immediately on discovery

Frequently Asked Questions

How do I get rid of caterpillars on houseplants?

Hand-pick caterpillars and egg masses immediately. Apply Bacillus thuringiensis (Bt) spray — a biological insecticide that specifically kills caterpillar larvae without harming beneficial insects. Repeat after 7–10 days for complete control.

What do caterpillars look like on plants?

You may see the caterpillars themselves (5–80 mm, various colours), irregular holes in leaves with ragged edges, or dark frass (droppings) on leaves. Check leaf undersides for egg clusters.