Pests and Disease: How to Control Fall Armyworm in Maize (Updated)

Tuesday, January 17, 2017

There are widespread media reports that the armyworm is threatening this season's maize production in many maize growing regions of Zimbabwe. The government has disbursed insecticides to some areas to prevent widespread crop failure. The same pest has already caused a national crisis in Zambia. We have received requests from emerging farmers asking for information on how to handle the armyworms in their maize. Instead of responding individually we thought it would be helpful to share information broadly here to help reduce major crop losses from our country's most important food crop.

Let's begin.

What is the Fall Armyworm (FAW)?

The armyworm is a destructive crop pest. The moth hatches a caterpillar which feeds on cereals such as maize. The caterpillars are about 3-4 cm long and have a velvety black shiny head with an inverted V-shaped mark on the head and white stripes along their sides and the back. They are called armyworms because they march in large numbers from the grass onto crops and can destroy entire fields of cereal crops such as maize, sorghum, and millet.

The other English name for the armyworm is the black worm. The local language names for the armyworm are imhogoyi or mhundururu.

  • Holes in the maize leaves and sometimes only the midribs of the maize plant are left in the more severe cases.
  • Outbreaks mostly occur after the first rains when grasses have started growing which armyworms need to multiply.


" An ounce of prevention is worth a pound of a cure."

  • Use resistant seeds: choose and plant disease resistant maize cultivars.
  • Planting time: plant early, late planted maize suffers from severe damage from second generation armyworms.
  • Weed early and often: but don't dig around the roots. Grassy fields are food for young caterpillars.
  • Companion planting: keep flowering broad-leaf plants around the fields as they host natural enemies of pests such as armyworms.
  • Sanitise: tools with bleach after use; remove and wash clothing to avoid spreading pests and disease.
  • Scout: your fields regularly especially in the early morning or late evenings when armyworm moths feed and are active. 
  • Prepare your land well: to expose and destroy armyworms.
  • Crop rotation: a 3-to 5-year rotation is best.
  • Don't burn grasslands: or you will destroy the natural habitats of armyworms.
  • Crop cleanup: at the end of the growing season remove plant debris. Keep your fields clean using cover crops.

When prevention fails and armyworms threaten to remove more than 20% of the leaves on your maize, you need to use biological or chemical controls to stop them.  Quick intervention is important to prevent widespread crop losses.

Biological and Physical Controls
  • Use insect traps: such as pheromone traps for early detection, and to attract insects. Check your traps weekly to monitor insect levels and begin to control them. 
  • Hand pick or gather the caterpillars in a container such as a jar. Fill the jar with very hot water or alcohol and set in the sun until the bugs die. This is feasible for small farms or small-scale production. 
  • Scout fields regularly and pick out and crush armyworm egg masses and larvae.
  • Dig a 30cm deep trench around the maize field to trap marching caterpillars and destroy them by crushing or burying them.
  • Sanitise: break of affected plants, and remove and destroy diseased leaves. Do not compost them, dispose of them in the garbage. Practice cleanliness in your fields such as using clean tools and washing your hands. 
  • Use light horticultural oil spray during the growing season to control armyworms. You can add it to BT for improved effectiveness.
  • Attract or buy beneficial insects (predatory and parasitic insects). Some natural predators of armyworms are praying mantis, ants, lacewings, parasitic wasps, flies, spiders, bats and birds. Grow plants in the carrot family ( herbs, dill, coriander) to attract beneficial bugs. 
  • Apply biopesticides (plant-derived) such as pyrethrin, neem or BT. Biopesticides are less toxic to humans and birds. 
    • Pyrethrin is a natural pesticide made from dried flowers that are ground into a powder, mixed with water and sprayed onto plants. Apply it directly to the armyworms, spraying the undersides of the maize plant leaves as well as the tops. Pyrethrin paralyses the armyworm on contact.
    • B.T. (Bacillus thuringiensis) gives excellent control of leaf-eating caterpillars like armyworms. It paralyses the armyworms' digestive system. Spray it to cover all plant surfaces entirely especially the undersides. Apply it to the infested plants every 10 to 14 days until pest is removed. Ask for locally available commercial formulations of Bt strains.
    • Use neem leaves. Neem is the extract of a tree native to Africa and Asia that controls most pests.  Crush 5 litres of mature neem leaves and soak them overnight, apply neem liquid as a spray or drench it on to young caterpillars. Neem restricts the appetite and growth of the armyworms.  
Chemical Controls: Approved Insecticides

Chemicals can be effective when applied correctly, but always try to use the least toxic methods first and chemicals as a last resort. Apply chemicals if damage exceeds more than 5% of the field.

Here is an updated list of recommended insecticides for fall armyworm (FAW) registered in Zimbabwe:
  • Ecoterex 0.5GR
  • Belt 480 SC
  • Belt Expert
  • Ampligo 150 ZC
  • Super Dash
  • Nemesis
  • Coragen 20SC
  • Blast Super
  • Aryna 46EC
  • Attitude 80SC
  • Steward 150EC
  • Missile 150SC
  • Devacarb 150SC
  • Blanket 150SC
  • Indoxacarb 150SC
5 Rules for Spraying Chemicals:
  • Use the least toxic product first
  • Keep chemicals out of the reach of children
  • Read the product label and use the product only on the plant, or plant type for which it is labelled
  • Follow instructions on the label
  • Wear protective gear: goggles respirator mask, gloves and long-sleeved shirts
Further reading

Keep track of armyworm forecasts on the Armyworm network page here.

Disclaimer: while Emerging Farmer does everything to ensure the accuracy of our guides, it is important to contact an agronomist or your Agritex officer for accurate recommendations for your farm. Emerging farmer takes no responsibility for any losses or damage incurred due to information in this guide.


  1. This blog is really helpful for all the farmers. Great information shared by you regarding symptoms, prevention and various methods used in pest controlling.

    pest control Bergen county

    1. Thank you for the feedback, Tapoutpestcontrol. We want to help more farmers prevent losses to pests.

  2. Thank you for providing solutions to get rid of pests and diseases. Pest Control Dallas TX has highly expert members who can solve all your problems easily.

    1. Good point Venus Pest. We do need to do more to share solutions with experts doing good work around the world. If you have any additional information or links please feel free to share it with us.

  3. Your blog are right, today's Pest Control is so important to protect types of diease . You have shared your experience after using Pest Control Services . Ecotechpestcontrol is also the best pest control company that offers effective and safe pest control services Chicago.

  4. ado koli 31,july2017 welldone am going to appied chloropyrifos to control army worms in my maize farm tomorow


Design by Studio Mommy (© Copyright 2015)