Common crops affected
What is it?
Armyworms (Spodoptera and relatives) feed gregariously on foliage and can strip a crop in days; cutworms (Agrotis) feed at night and cut seedlings off at the base. Both are moth larvae whose populations can erupt after migratory moth flights.
How to identify it
- Seedlings cut off at the soil line
- Ragged, rapid defoliation in patches
- Larvae hiding in soil/debris by day
- Frass near damaged plants
Life cycle & spread
Moths migrate and lay egg masses; larvae develop over 2-4 weeks, then pupate in the soil. Several generations occur per season, and outbreaks often follow weather that concentrates moth flights.
Conditions that favour it
Outbreaks follow heavy moth flights, mild wet springs (cutworm) and lush early growth. Weedy fields and debris give larvae shelter.
Damage and how it spreads
Armyworms cause rapid defoliation; cutworms cause stand loss by severing seedlings — both can happen overnight, sometimes requiring replanting.
Monitoring & scouting
Scout at dusk or early morning; check soil and debris near cut plants; use pheromone traps for moth flights. Target early instars before they disperse.
How to control it
- Treat early instars promptly;
- address both the foliar and soil stages where present;
- keep field margins and debris clean to reduce shelter.
Recommended Vegalab solution: Larva Control
Vegalab Larva Control — Larva Control (oxymatrine), targeting young larvae at dusk before they grow and disperse; repeat on the label interval through the generation.
Results you can mention: Larva Control (oxymatrine) has been university-evaluated against beet armyworm (Spodoptera exigua), and field-trialled against caterpillar pests versus conventional standards.
| Role | Product | Use |
|---|---|---|
| Primary control | Larva Control | |
| Also apply | Larva BioControl |
Preventing it next season
Early scouting after moth flights, clean field margins and debris, and prompt treatment of early instars before stand loss.
Claims and product availability vary by jurisdiction. Always read and follow the product label.