Most of the worms that eat crops are not true worms at all. They are caterpillars, the larvae of butterflies and moths, that hatch from tiny eggs and feed voraciously on leaves, fruit and stems. Just a few days of delay in spotting them can leave a whole field with leaves reduced to perforated skeletons.
In this guide we cover the main worms and caterpillars that attack vegetables, cotton, corn and field crops, how to tell them apart by their damage symptoms, and the general control steps. Each type has a detailed article, and you will find its link under its name.
Quick Overview
Main pests: Tuta absoluta, fall armyworm, cotton leafworm, American bollworm, cutworm, diamondback moth, and leaf miners.
Affected crops: Tomatoes, corn, cotton, cabbage, leafy vegetables, potatoes and many field crops.
Symptoms: Perforated or chewed leaves, tunnels inside the leaf, stems cut at soil level, and fruit with holes and droppings.
Key step: Early scouting at night or at dawn, and collecting eggs and small larvae before they multiply.
What Types of Worms and Caterpillars Eat Crops?
These pests are all larvae that feed on the plant, but they differ in where they attack and in their preferred crop:
Tuta absoluta
Small larvae that mine tunnels in tomato leaves, fruit and stems, and spread quickly in greenhouses and open fields.
Fall Armyworm
Voracious larvae that attack corn and other crops, feeding on leaves and growing tips and sometimes boring into ears.
Cotton Leafworm
The moth lays eggs in masses covered with hairs, and the larvae feed on leaves and fruit in many crops.
American Bollworm
Larvae that bore into bolls, fruit, ears and buds, directly damaging the productive part of the plant.
Cutworm
Larvae that live in the soil and come out at night to cut young seedlings at ground level.
Diamondback Moth
A small moth that lays its eggs on cabbage, cauliflower and the rest of the cabbage family, and its larvae chew holes in the leaves from underneath.
Leaf Miners
Tiny larvae that live between the two surfaces of the leaf and draw winding white tunnels that look like lines.
How Do I Recognize a Caterpillar Infestation?
The damage is the first thing you notice, but finding the larva itself settles the species:
- Irregular holes or chewed edges in the leaves.
- Winding white tunnels inside the leaf, which point to leaf miners.
- Seedlings cut at soil level or suddenly wilted.
- Round holes in fruit or ears with black droppings.
- Egg masses or silken threads on the underside of leaves.
- Larvae that hide under leaves or in the soil during the day and become active at night.
Search at night or in the early morning with a flashlight, because many of these larvae do not show up in broad daylight.
What Damage Do Worms and Caterpillars Cause to Crops?
- Loss of leaf area, which weakens the plant and reduces its ability to set fruit.
- Damaged fruit and ears, and lower crop quality and price.
- Cut seedlings, which forces replanting.
- Open wounds that let fungi and bacteria in.
- Resistance to pesticides that develops when the same active ingredient is sprayed repeatedly.
How Do I Get Rid of Worms and Caterpillars?
Control success depends on timing, because small larvae are far more sensitive than large ones:
- Identify the species before spraying, because each caterpillar behaves differently and needs a different treatment approach.
- Hand-pick egg masses and visible larvae and destroy them in small areas.
- Use pheromone traps to monitor the moths and time the treatment.
- Biological products containing Bacillus thuringiensis can be used in the early stages.
- When a chemical pesticide is needed, choose a group registered for the crop and the pest, and follow the label instructions and the pre-harvest interval.
- Rotate between pesticide groups with different modes of action to reduce resistance.
How Do I Prevent Worms and Caterpillars From Coming Back?
- Till the soil after harvest to expose pupae to drying and to birds.
- Remove crop residues and weeds that shelter the larvae.
- Rotate crops and do not plant the host crop in the same field season after season.
- Use protective nets in greenhouses and seedling nurseries.
- Inspect seedlings before planting and destroy any plant carrying eggs or tunnels.
- Protect natural enemies by avoiding broad-spectrum, indiscriminate spraying.
If you are not sure which caterpillar you are dealing with, or you need a plan that suits your crop, contact the Orkida Agri engineers on WhatsApp and send clear photos of the infestation, and we will guide you to the right step.
Image source: Shutterstock
Frequently Asked Questions About Worms and Caterpillars in Crops
How do I know caterpillars are the cause of crop damage?
Look for chewed leaves or holes in the fruit, small black droppings on the leaves, and larvae hiding on the underside of leaves or inside the fruit. Scouting works best in the early morning or evening.
When should I start control?
At the first sign of small larvae or the first signs of chewing, because small larvae are easier to control than large ones, which hide and feed voraciously.
Is one pesticide enough for all types of caterpillars?
No. The species differ in behavior and sensitivity, with some feeding on leaves and others inside fruit or in the soil, so the pesticide is chosen according to the species and the crop.
How do I prevent caterpillars from coming back?
Through field sanitation and removing the previous crop's residues, using pheromone traps for monitoring, rotating active ingredients between sprays, and inspecting seedlings before planting.