Pestipedia

Velvet Bean Caterpillars

**Velvet Bean Caterpillars** (*Anticarsia gemmatalis*) are major insect pests of legumes, particularly **soybeans** and peanuts, across the Americas. They are the larval stage of a tan or gray moth. The conflict is **rapid defoliation and yield loss**: the caterpillars feed voraciously on soybean foliage during the critical pod-filling stages, consuming leaf tissue and causing rapid defoliation that can significantly reduce soybean yield if left unchecked.

Taxonomy and Classification

Velvet Bean Caterpillars belong to the Order Lepidoptera (Moths and Butterflies) and the Family Erebidae (Owlet Moths). They undergo complete metamorphosis.

Physical Description

Larvae are up to 40 mm long.

  • **Adult (Key ID):** Nondescript, brownish-gray moth with a distinctive diagonal line across the forewing.
  • **Larva (Key ID):** Green, olive, or black caterpillar with pale longitudinal stripes; very **twitchy and active**, often wriggling or jumping when disturbed; possesses five pairs of prolegs.
  • **Damage ID:** Ragged holes in leaves; severe defoliation during late summer/early autumn.
  • **Conflict:** Agricultural.

Distribution and Habitat

Found in North, Central, and South America, especially in the southern US and Brazil. Habitat is large agricultural fields growing soybeans, peanuts, velvet bean, and other legumes.

Behavior and Conflict

The conflict is driven by their high consumption rate.

  • **Migration:** They are non-overwintering pests in northern regions and migrate north annually from tropical areas.
  • **Voracity:** Late instar larvae can consume large amounts of foliage quickly, causing rapid damage accumulation.

Management and Prevention

Management is **Integrated Pest Management (IPM) and Economic Threshold**.

  • **Monitoring (Key):**
    • Regularly scouting fields and using sweep nets to assess larval numbers against established economic thresholds before applying control measures.
  • **Chemical Control:**
    • Application of targeted insecticides only when the economic threshold is crossed to preserve beneficial insects.

    • Conservation and Research

    Research focuses on identifying **natural biological controls** (e.g., parasitic wasps, entomopathogenic fungi) and developing genetically modified (Bt) soybean varieties that are resistant to feeding.