Caterpillar Pests

Caterpillars can strip a crop in days — but you don't need harsh chemicals to stop them. Learn to spot the damage early and exactly how to get rid of caterpillars with proven biological control that's safe for your plants, your pollinators, and your harvest.

You may know them as loopers, armyworms, cutworms, or borers — all are moth and butterfly larvae, and only the larval (caterpillar) stage damages your crop, since the adult moths feed on nectar. In a warm greenhouse or grow room a single moth-flight can turn healthy foliage into lace almost overnight, but once you know what to look for, caterpillars are one of the most predictable pests to beat naturally.

How to identify caterpillar damage

Watch for chewed leaf edges and ragged holes, skeletonized leaves, rolled or webbed foliage, and boreholes in stems, buds, or fruit. The clearest giveaway is caterpillar damage paired with pellet-like green or black frass (droppings) scattered on the leaves below. Check leaf undersides for clusters of eggs and tiny young larvae — catching them small is the difference between a quick fix and a salvage job.

Why caterpillars keep coming back

Adult moths fly in and lay eggs continuously through the season, so squashing the caterpillars you can see never stops the next wave. Larvae also hide inside rolled leaves, stems, and fruit where contact sprays can't reach, and many populations now shrug off chemical insecticides. That's why a spray-only program feels like an endless battle.

How to get rid of caterpillars naturally

Timing is everything. Release Trichogramma egg-parasite wasps before the eggs hatch — use pheromone traps or degree-day models to predict moth-flight — then bring in lacewings and a Bt-type biopesticide once larvae are active. Hit the egg stage and the damage never starts, and because beneficials leave zero residue, you can keep using them right up to harvest, even on cannabis and food crops.

Beneficials that stop caterpillars

Build your program from the proven, ready-to-release biocontrols in this collection:

• TRICHOforce (Trichogramma) — tiny parasitic wasps that destroy caterpillar (moth) eggs before they ever hatch. Your first line of defense, timed to moth flights.
• Green lacewing larvae (CHRYSOforce R) — voracious generalist predators that devour caterpillar eggs and young larvae; also available as eggs on cards for economical coverage and adults to seed a population.
• SuffOil-X — a ready-to-use horticultural oil for a soft, beneficial-friendly knockdown of eggs and small larvae.

Want a complete, step-by-step program? Explore the full Caterpillar Control collection.

Frequently asked questions

What kills caterpillars but not plants?

Targeted biologicals do: Bt (a caterpillar-specific bacterium), Trichogramma egg-parasite wasps, and green lacewings all kill caterpillars without harming plants, people, or pollinators.

What is the natural predator of caterpillars?

Parasitic wasps like Trichogramma, green lacewings, and predatory bugs are the main natural enemies (along with birds outdoors). Released beneficials give reliable, targeted control indoors and in greenhouses.

What is the fastest way to get rid of caterpillars?

Hand-pick what you can, apply a Bt-type spray to active larvae, and release Trichogramma timed to moth flights so the next generation never hatches.

Will caterpillars go away on their own?

In a backyard garden, natural predators often keep them in check. In a commercial crop they reproduce and feed too fast to wait — start monitoring and releasing beneficials early.

What causes caterpillars on plants?

Egg-laying moths drawn to host crops. Warm seasons, continuous plantings, and nearby weeds let generation after generation build up.