Common crops affected
- Cotton
- Corn
- Tomato
- Pepper
What is it?
Cotton bollworm is the larval stage of Helicoverpa moths — among the most damaging and widely distributed caterpillar pests in the world. The same insect is called corn earworm in maize and tomato fruitworm in tomatoes. Females lay eggs singly on tender new growth and flowers, and the emerging larvae move quickly to feeding on reproductive structures.
How to identify it
- Pearl-white, dome-shaped eggs laid singly on new growth, silks and flower buds.
- Young larvae feeding on leaves, buds and flowers before boring inward.
- Larger larvae (up to ~40 mm) boring into bolls, ears or fruit, with colour ranging from green to brown with pale stripes.
- Frass (droppings) at entry holes and hollowed or rotting reproductive structures.
Life cycle & spread
Multiple overlapping generations occur in warm conditions. Moths are strong fliers that migrate into crops, lay eggs on reproductive tissue, and larvae complete development in 2-4 weeks before pupating in the soil. Continuous cropping sustains year-round pressure in warm regions.
Conditions that favour it
Warm temperatures and flowering/fruiting crop stages drive population build-up. Pressure peaks when susceptible reproductive tissue coincides with moth flights.
Damage and how it spreads
Larvae destroy the highest-value tissue — bolls, ears and fruit — causing direct, often severe yield and quality loss. Entry wounds also open the door to secondary rots.
Monitoring & scouting
Use pheromone traps to time moth flights; scout new growth and flowers for eggs and early instars. The control window is egg-hatch to early instar, before larvae bore in and become protected.
How to control it
- Act before larvae enter bolls/fruit — once inside they are shielded from contact products.
- Conserve natural enemies, rotate modes of action for resistance management, and time the first application to early instars.
Recommended Vegalab solution: Larva Control
Larva Control — natural broad-spectrum larvicide (oxymatrine, from Sophora flavescens); foliar spray at the start of larval occurrence, targeting eggs and early instars with thorough coverage of foliage and reproductive structures.
| Role | Product | Use |
|---|---|---|
| Primary control | Larva Control |
Preventing it next season
Pheromone trap monitoring, early scouting of reproductive tissue, and a timely first spray before larvae bore in. Destroy crop residues that harbour pupae.
Claims and product availability vary by jurisdiction. Always read and follow the product label.