Spodoptera frugiperda
5
Damage Signs
5
Organic Methods
4
Chemical Options
5
ID Tips
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FAQs
7
Crops Affected
Updated February 2026
Vous voyez Fall Armyworm sur vos plantes ?
Téléchargez une photo pour une identification instantanée avec méthodes de lutte biologiques et chimiques.
Overview
The most devastating invasive pest to hit Africa in decades. Fall armyworm (FAW) arrived in West Africa in 2016 and spread across the entire continent within two years, causing billions of dollars in maize losses. Native to the Americas, FAW is a voracious feeder that attacks over 350 plant species, with maize as its preferred host. A single larva can destroy an entire maize plant's growing point. FAW moths are strong flyers, capable of traveling 500 km in a single night, making containment impossible once established.
Field Guide
Larvae are light green to brown caterpillars (25-35 mm at maturity) with a distinctive inverted Y-shaped marking on the head capsule and four dark spots arranged in a square on the second-to-last abdominal segment. Moths are grayish-brown with a wingspan of 32-40 mm; males have a distinctive white patch on the forewing.
Look for the inverted Y marking on the larval head capsule — this distinguishes FAW from other armyworms
Check for four dark spots in a square on the second-to-last abdominal segment
FAW frass is wet and visible in the whorl — African armyworm frass is drier
FAW larvae are typically found INSIDE the whorl, not on exposed leaf surfaces
Use pheromone traps (FAW-specific lures) to monitor adult moth activity
Scouting Guide
Ragged holes in leaves with large amounts of wet frass (caterpillar droppings) visible in the leaf whorl
Destruction of the growing point (dead heart) in young maize plants
Window-paning of leaves — larvae scrape one surface, leaving translucent 'windows'
Bored ears with frass-filled tunnels and damaged kernels
Plants with whorl damage showing ragged, torn appearance
Biology
Complete metamorphosis: egg (3 days) → 6 larval instars (14-21 days) → pupa in soil (8-14 days) → adult moth (10-21 days). Total generation time 30-60 days. In tropical Africa, FAW breeds continuously year-round with no diapause, producing 4-6 generations per year.
Pest Management
Hand-picking and crushing larvae
In small plots, inspect whorls daily and physically remove and crush larvae. Most effective when plants are young and infestations are light.
Bt (Bacillus thuringiensis) spray
Apply Bt kurstaki at 1-2 g/L targeting young larvae (1st-3rd instar) in the whorl. Spray in the evening when larvae are actively feeding. Repeat every 7-10 days.
Neem extract application
Apply neem seed kernel extract (50 g crushed neem seeds per liter water, filtered) into the whorl. Neem acts as a feeding deterrent and growth disruptor.
Push-pull technology
Intercrop maize with Desmodium (silverleaf) as 'push' plant and border rows of Napier/Brachiaria grass as 'pull' plant. Desmodium repels FAW moths; border grasses attract them away from maize.
Natural enemies and biocontrol
Encourage natural parasitoids (Telenomus remus egg parasitoid, Cotesia icipe larval parasitoid) and predators (earwigs, ants, spiders). Avoid broad-spectrum insecticides that kill beneficials.
Use as last resort. Follow label instructions. Wear protective equipment.
Chlorantraniliprole (Coragen 20SC)
Apply at 0.4 ml/L into the whorl when 2nd-3rd instar larvae are detected. Highly effective, selective, and safe for beneficial insects. The preferred chemical option.
Emamectin benzoate (Proclaim 5SG)
Apply at 0.5 g/L targeting young larvae. Systemic and translaminar activity provides 10-14 days of protection.
Spinosad (Tracer 480SC)
Apply at 0.5 ml/L into the whorl. Derived from soil bacterium (Saccharopolyspora spinosa). Effective on young larvae, moderate impact on beneficials.
Lambda-cyhalothrin (Karate 2.5EC)
Apply at 1 ml/L as emergency knockdown spray for severe infestations. Broad-spectrum — kills beneficial insects. Use only as last resort.
Host Range
Fall Armyworm can attack 7 crop species.
Common Questions
FAW was first detected in West Africa (São Tomé and Nigeria) in early 2016, likely arriving via trade or weather systems from the Americas. By 2018, it had spread to all 54 African countries. The exact pathway of introduction is unknown, but DNA analysis confirmed the population originated from the Western Hemisphere.
No. FAW has permanently established in Africa and will never be eradicated. It breeds year-round in tropical Africa with no diapause, and adults can fly 500 km per night. The focus is on integrated management to keep damage below economic thresholds, not eradication.
Yes. Research by ICIPE in Kenya showed that the push-pull system (Desmodium intercrop + Brachiaria border) reduces FAW damage by 80%+ while also controlling striga weed and stemborers. It is the most sustainable long-term solution for smallholder maize farmers in Africa.
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