Caterpillars and Chewing Insects 🐛
Mostly order lepidoptera larvae, plus other chewing insects
At a glance
- Looks like: Ragged holes, missing leaf edges, skeletonized patches, or chewed buds
- Tell-tale sign: Frass pellets, rolled/folded leaves, or an actual larva hiding nearby
- Severity: Usually minor outdoors; serious on seedlings, vegetables, and young restoration plants
How to identify
Chewing insects remove tissue outright rather than stippling, mining, or coating leaves. Look for irregular holes, clipped tender growth, skeletonized leaves, rolled leaves, and dark pellet-like frass. Caterpillars often hide on leaf undersides, in folded leaves, or deep in buds during the day.
Damage
Most established landscape plants tolerate some chewing. Seedlings, soft houseplant growth outdoors, young native plantings, and vegetables can be set back quickly if the growing tips are eaten.
Treatment (least-toxic first)
Following Integrated Pest Management:
- Confirm who is feeding; a few native caterpillars may be worth tolerating on wildlife plants.
- Hand-pick or prune out small colonies when damage is localized.
- Protect seedlings physically with collars, mesh, or temporary covers.
- Use Bacillus thuringiensis kurstaki (Bt) only on actively feeding caterpillars when needed; it must be eaten and can affect butterfly/moth larvae.
- Avoid broad sprays on habitat plants where beneficial insects and pollinators are the goal.
Prevention
Inspect new flush and seedlings. Keep young restoration plants protected until established, and decide whether the plant is a host plant before treating.
Affects (in this guide)
Seedlings, vegetables, soft herbaceous growth, and occasional young natives; many caterpillars are also wildlife value