How to get rid of Fall armyworms

A picture of a fall armyworm caterpillar on a maize crop whorl

The Fall Armyworms, Spodoptera frugiperda, is one of the worst crop pests in Kenya. Since its first appearance in 2015-16 season, it has caused huge financial and crop damages for maize, wheat, rice and other cereal farmers.

In this post, learn how to control or manage the Fall Armyworms in your field. We have categorized the post in two sections. First is to understand the FAW infestations including its occurrence in Kenya, damages caused, the insect’s behavior and their life cycle. The second part deals with methods of managing and controlling FAW in Kenya.

  • Understanding the Fall Armyworms
    • Spread of FAW in Kenya
    • Damage
    • Identifying the FAW
    • FAW Behavior
    • The FAW Life cycle
  • Managing and controlling Fall Armyworms pests
    • Cultural control methods
    • Biological Control Methods
    • Pesticide Control methods

Spread of Fall Army worms in Kenya

The FAW are not native to the East Africa Region. The figure below shows the appearance and spread of FAW In Kenya over time and Space.

The FAW were first observed in 2015 in western Kenya. They followed an immigration route towards East to cover the entire maize growing counties in less than three years. In the second year, 2016, there were numerous sightings in high rainfall areas of western and central Kenya. They later spread into moist mid-altitude, moist transitional later in the year. By 2017, the FAW pests had covered the dry areas and coast counties.

A map showing the Spread and infestation of Fall Armyworms in Kenya between 2015-2018
Spread and infestation of Fall Armyworms in Kenya Source; science direct

Damage of FAW pests to Kenya’s Maize production

FAW causes many challenges to both livestock and crop farmers. These include

  • Poor cereal yields as result of maize, rice and wheat etc. destruction.
  • Reduced farmers income from high cost of pest control and poor yields
  • Defoliation of graze-able pasture to feed livestock.
  •  Eyesore Brown patched lawns (resembling drought) for homeowners.

Previous studies estimate that Kenya is losing more than a third of its annual maize production to FAW. This translates to more than 1 million tons of maize each year. Maize losses to FAW were 924,000 tons (34%) in the long rains of 2017, and 883,000 tons (32%) in the same season of 2018.  

Which crops do FAW foliage on?

There are two major strains of FAW: the rice strain and the corn strain. The corn FAW is the key strain in the region destroying maize. The larvae usually feed on tender corn leaves. They may attack the tassels and/or ears of corn. In case of Severe feeding, corn fields may appear to have been damaged by hail. Other crops that FAW destroy are the pearl millet, sorghum, wheat, rice,

Identifying the FAW

The fall armyworm moths have dark gray, mottled forewings with light and dark splotches. Unlike other moths, they have a noticeable white spot near the extreme end of each wing.

There are several species of armyworm caterpillars. The Newly hatched Spodoptera frugiperda larvae are green in color and move in a looping motion. They are smooth-skinned and vary in color from light tan or green to nearly black. Their distinctive feature is their head. The FAW has a predominant white, inverted Y-shaped suture between the eyes. In addition, they have three yellow-white hairlines down their backs. On each side of their bodies and next to the yellow lines is a wider dark stripe. Next to that is an equally wide, wavy, yellow stripe, splotched with red. Full-grown larvae are about 1-1/2 inches (38 mm) long.

The other easy way to identify a FAW attack from other armyworms is their behavior. They will damage corn patches.

The FAW Behavior

To understand the most effective methods to control Fall Army worms’ caterpillars, its best to understand their behavior.

Feeding; Fall armyworms actively feed early in the morning, late in the afternoon, or in early evenings.

Infestation: Fall armyworms appear and disappear suddenly in fields which can be termed instant or overnight. It because younger worms cause minimal damage while older caterpillars cause huge damage.  Mature caterpillars disappear suddenly by either burrowing into ground to pupate or moving on to the next fields in search of food.

Reproduction: Armyworms are very prolific under conducive weather and feeding conditions. Their lifecycle is short, adult’s eggs are laid in fluffy masses on crowns of seedlings and on leaves of older plants. In 5-10 days, tiny caterpillars hatch and feed for several weeks. They then pupate and emerge as adults 10 days later. You may have to deal with three or more generations each corn growing season.

The Fall Armyworms lifecycle

The FAW lifecycle is similar to other insects. They have a four-stage cycle of adults, eggs, larvae and pupae. Their larvae or caterpillar is the most destructive to farmers. These cycles are explained below.

Adult. The adult FAW is an ash gray moth. They are most active at twilight. They live for an average life span of 2-3 weeks since they molt from pupae. Thy mostly feed on nectar.

Eggs. The female FAW moths lay most of their eggs on day 4-9 after they emerge from the pupal stage. They mostly lay on light colored surfaces. The eggs are light gray and are covered with a greyish fuzz. With time they tend to darken. The FAW eggs hatch within 2-4 days.

Larvae. FAW caterpillars are tiny, light colored and black headed at hatching. They will feed for about 14 days. They will feed most during their last 4 days before they can pupate. For other features see the section on how to identify the FAW.

Pupae. Mature larvae will burrow in soil to form the pupae. Adult moths will mature in around 10 days.

Having understood the features, behavior and the Fall Armyworm lifecycle, you will learn some of the common pest control and management methods. Around the world, farmers either use pesticides, biological or cultural methods. Their pest control aims are to keep the FAW populations low and their destruction below economical losses. 

Most Farmers use a combination of both cultural and chemical pesticides to control Fall Armyworms (FAW) infestations.

Cultural Methods of controlling FAW

Maize fields that are free from weeds and crop residues suffer little FAW infestation

Farmers use a combination of various control methods to control FAW pests. The cultural methods in use include

  • Plant your maize at the onset of rains. Studies show that late-planted and off-season crops suffer heavy infestations. Planning for the early vegetative growth to coincide with heavy rainfall. It is known to suppress FAW by drowning the worms.
  • Ensure maize fields are free from weeds and crop residues. Consider plowing and furrowing your farm early enough to expose any FAW eggs or pupae to sun heat. In Zimbabwe, FAW infestation on maize fields was found to be significantly reduced by timely weed control
  • Intercrop maize or sorghum with legumes (beans, cowpeas, green grams, Dolichos) to reduce the chances of the pest finding the host. This also enhances the population of natural predators. Climate adapted push-pull method reduces damage of FAW with over 86.7% success rate on a study conducted in Kenya, Uganda and Tanzania.
  • Some Farmers apply wood ash to the maize whorl at a rate of 2kg/ha Besides reducing FAW they report this method to control other insects including aphids and promotes rapid growth rate.
  • A few farmers use plant (organic) extracts such as those from pepper, Bidens Pilosa, and neem tree, etc.
  • Spraying a combination of powder detergents (“Omo, Aerial”) and water. To improve on efficacy, some farmers report to add tobacco leaves and baking powder (sodium bicarbonate) to the concoction
  • Soil paste application on the maize whorl is used but is not considered effective.
  • In central America, a combination of various methods like minimum tillage, biomass mulching, intercropping, and diversification of the farm environment through crop rotation were effective control methods.

Biological control methods for FAW

  • Some small-scale farmers release their Chickens to the maize fields to prey on FAW. However, it is reported that the poultry ma may cause damage to the maize plants.
  • Some farmers pour cooking oil on base of the maize plants as to attracts ants which prey on FAW.
  • Most large-scale farmers in Latin America prefer use of Genetically modified organisms

Best pesticides for controlling FAW in Kenya

Use of farm chemicals or pesticides is the most common method of controlling FAW infestations. Below is the list of the approved insectoids by PCPB for controlling FAW in Kenya. Farmer are advised to keep changing the products used. Besides, read and understand the products labels to use the product effectively and safely to avoid personal harm or contaminating the environment.

  • Belt (flubendiamide): it is sparingly used and reported as efficacious; not widely available; very expensive.
  • Coragen (chlorantraniliprole): used and reported as efficacious; not available.
  • Duduthrin (lambda-cyhalothrin): this product is widely used.
  • Escort (emamectin benzoate): used and reported as efficacious; not widely available
  • Match (lufenuron): used and considered effective, but not widely available.
  • Orthene/Ortran (acephate): used and considered effective.
  • Lotus (Acephate) mix 20ml in 20l of water
  • Radiant ISpinetoram) mix 20ml in 20l water


Looking for additional information about Integrated Pest Management (IPM) Options for Fall Armyworms in Kenya? Download the following PDF documents

Post a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.