Variegated Cutworm

Agrotis (=Peridroma) saucia

1. Identification

• Common name: Variegated cutworm
• Scientific name: Peridroma saucia Hübner
• Synonym: Agrotis saucia Hübner
• Order: Lepidoptera
• Family: Noctuidae

2. Pest description

• Caterpillars of variable colour, from brownish-green to grey, with a smooth, glossy body, reaching about 40 mm, curling into a “C” shape when disturbed.
• Adults with a 35–45 mm wingspan, brownish or greyish forewings with a characteristic variegated pattern and pale hindwings.
• Polyphagous species that attacks several vegetable and industrial crops, especially at early stages.
• Caterpillars live in the soil and feed at the collar level of the plants, cutting them partially or completely.
• It may have several generations per year, with greater incidence in spring and autumn.

3. Main hosts

• Vegetables such as lettuce, cabbages, spinach, carrot, beet, tomato and pepper.
• Extensive crops such as maize, potato and tobacco.
• Weeds that can serve as a reservoir.

4. Symptoms and damage

• Cutting of seedlings at soil level, causing planting gaps.
• Young plants partially gnawed or toppled due to feeding at the collar.
• Superficial borings in roots and tubers.
• Significant damage in seedbeds and transplants, which may compromise crop establishment.

5. Biological cycle

• Eggs laid in the soil or at the base of the plants.
• Caterpillars develop in the soil, where they remain throughout the larval cycle.
• Pupation also in the soil.
• Adults with nocturnal activity, attracted to light, with frequent flights during mild periods.
• Development favoured by moist soils and moderate temperatures.

6. Monitoring

• Observation of plants cut at soil level in seedbeds and transplants.
• Superficial digging next to affected plants to detect caterpillars.
• Light traps to detect adults and track flights.
• Pheromone traps to monitor population peaks.
• Assessment of the percentage of affected plants at the early stages of the crop.

7. Management measures

• Cultural: superficial soil tillage to expose caterpillars and pupae, removal of weeds, management of organic matter and choice of sowing periods less favourable to the pest.
• Preventive: use of more developed plants at transplanting, practices that promote good rooting and maintenance of soil conditions that hinder caterpillar survival.
• Biological: conservation of natural enemies such as ground beetles and insectivorous birds, and use of selective biological products such as Bacillus thuringiensis at early stages.
• Integrated protection: monitoring with pheromones and light traps, definition of intervention thresholds and careful application of authorised insecticides targeting the soil and the most sensitive stages of the pest.

Bibliographic references

• CABI – Invasive Species Compendium – Agrotis saucia.
• EPPO Global Database – Agrotis saucia.
• Capinera, J. L. (2001). Handbook of Vegetable Pests. Academic Press.
• Lafontaine, J. D. & Schmidt, B. C. (2010). Annotated Check List of the Noctuoidea of North America. ZooKeys, 40, 1–239.
• Pogue, M. G. et al. (1995). Biology and management of variegated cutworm (Agrotis saucia). Journal of Economic Entomology, 88, 145–152.