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Pest · Insect pest

Fall Armyworm

Spodoptera frugiperda (Lepidoptera: Noctuidae)

Also known as: FAW

Fall armyworm is a highly mobile moth whose caterpillars feed in the whorl and ear of maize and other cereals, and which has spread to become a major pest across much of the world.

Dated referenceLast reviewed: 2026-07-12Updated: 2026-07-12
A fall armyworm caterpillar
Wee Hong, via Wikimedia Commons (CC BY-SA 4.0) CC BY-SA 4.0 (opens in a new tab) source (opens in a new tab)Downloaded from Wikimedia Commons; resized to a maximum width of 1280 px and recompressed as JPEG for web delivery. Content unaltered.Illustrative only — visual symptoms or appearance alone may not be sufficient for reliable identification.

Fall armyworm is the caterpillar stage of a night-flying moth native to the Americas. Adult moths are strong fliers capable of migrating long distances on seasonal winds, which has allowed the species to establish across Africa, Asia, and Oceania since 2016 after previously being confined to the Americas.

Larvae feed on a wide range of grasses and cereals but are best known as a major pest of maize, where feeding in the whorl and later in the ear can cause substantial yield loss if left unmanaged. Rapid reproduction and long-distance migration make it a particularly challenging pest to track and manage regionally.

Identification

Larvae vary in colour from light green to nearly black but usually show longitudinal stripes along the body. Two features help distinguish fall armyworm from similar caterpillars: a pale, inverted Y-shaped marking on the head capsule, and four dark spots arranged in a square on the segment just before the last.

FeatureFall armywormMany similar caterpillars
Head capsule markingPale, inverted Y shapeMarking usually absent or different
Segment before the lastFour dark spots forming a squareSpots, if present, not arranged in a square
Distinguishing fall armyworm larvae from look-alike caterpillars

Biology and life cycle

Females lay egg masses covered in protective fuzzy scales, usually on leaves. Larvae pass through six instars before pupating in the soil, and in warm conditions a generation can complete in under a month, allowing several overlapping generations per growing season.

Fall armyworm cannot survive prolonged freezing temperatures, so in cooler regions populations typically recolonize each season through migration from warmer areas rather than overwintering locally.

Damage and hosts

Young larvae scrape the leaf surface, producing a translucent "window-pane" effect, while older larvae chew ragged holes and burrow into the whorl, leaving characteristic coarse frass. Larvae can also feed directly on developing ears, adding to yield impact.

The host range spans many grasses and cereals. Maize is the most heavily affected crop in most regions, with sorghum and rice also recognized as significant hosts among many others.

Monitoring

Pheromone traps are widely used to track adult moth flight activity and help anticipate egg-laying periods. Field scouting focuses on the whorl stage, looking for early feeding signs and frass, with local economic thresholds guiding whether intervention is warranted.

Because of its migratory capacity, fall armyworm is also tracked through regional and international monitoring networks that share flight and outbreak information across borders.

Management principles

Fall armyworm management combines biological, cultural, and monitoring-based tactics within an integrated pest management framework.

  • Conserve parasitoid wasps, predators, and naturally occurring pathogens
  • Scout regularly at the whorl stage, when early intervention is most effective
  • Use locally recommended resistant or biotech varieties where authorized
  • Practise field sanitation and timely planting to reduce carry-over
  • Participate in area-wide monitoring given the pest’s migratory behaviour

Relationships

Evidence-backed connections in the knowledge graph.

Affects

Risk increases under

Managed with

Related topics

Scope & limitations

Geographic scope: Global overview of a highly mobile pest now established across the Americas, Africa, Asia, and parts of Oceania; local hosts, pressure, and guidance vary by region.

Climate context: Warm temperatures speed development and allow more generations per season, while seasonal winds carry moths into cooler regions where the pest cannot overwinter.

  • This is a general overview of a widely distributed migratory pest, not region-specific guidance for a particular country or cropping system.
  • Thresholds and control-product recommendations are jurisdiction-specific and are not provided here.

Sources

This article draws on the following authoritative sources. See our sources & methodology for how they are selected.

  1. [1]FAO — Food and Agriculture Organization (opens in a new tab)

    Food and Agriculture Organization of the United Nations (FAO)

    Authoritative

    Cited for: Global distribution and monitoring guidance

    Type:
    Intergovernmental organization
    Jurisdiction:
    Global
    Accessed:
    2026-07-12
  2. [2]USDA APHIS — Animal and Plant Health Inspection Service (opens in a new tab)

    USDA Animal and Plant Health Inspection Service (APHIS)

    Authoritative

    Cited for: Pest status and regulatory context

    Type:
    Government agency
    Jurisdiction:
    United States
    Accessed:
    2026-07-12
  3. [3]CABI Digital Library — Crop Protection Compendium (opens in a new tab)

    CABI (Centre for Agriculture and Bioscience International)

    High

    Cited for: Biology, hosts, and identification

    Type:
    Reference database
    Jurisdiction:
    Global
    Accessed:
    2026-07-12
  4. [4]CIMMYT — International Maize and Wheat Improvement Center (opens in a new tab)

    International Maize and Wheat Improvement Center (CIMMYT)

    High

    Cited for: Maize-specific impact and management research

    Type:
    Research institute
    Jurisdiction:
    Global
    Accessed:
    2026-07-12

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