Two years ago, the voracious caterpillar emerged in southern Africa. Since then, it has spread to 38 countries on the continent. The World Food and Agricultural Organization is warning of imminent crop failures.
Image: Natalie Hummel/Louisiana State University AgCenter/Bugwood.org
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The fall armyworm (Spodoptera frugiperda) is likely to cause great damages to the harvest this year and in the coming years. That's what Jean-Baptiste Bahama, a representative of the UN Food and Agricultural Organization (FAO) in the Ethiopian capital Addis Ababa, told German news agency DPA. The caterpillar attacks primarily corn, which is the most important staple food in Africa.
The fall armyworm originates in the tropical and subtropical regions of America. In Africa, it first emerged in Nigeria in 2016. Since then it managed to spread to 38 African countries. In July of this year, the parasite has even been sighted on Cap Verde, a group of islands in the Atlantic off the western African coast.
South of the Sahara, the FAO expects crop failures amounting to losses in the billions for the coming years.
"The amount of damage is of great concern, especially in those countries where most farms are small and farmers have little access to effective pesticides," Bahama said.
Half of the crops could get destroyed
Each year, the caterpillars could destroy between eight and 21 million metric tons of corn, the FAO estimates. Usually the harvest reaches 39 million tons. Financially, that would amount to losses between 2.5 and 6.5 billion dollars for the farmers, Bahama estimates.
The fall armyworm eats his fill very quickly and then pupates. As a moth it can travel as far as 100 kilometers in just one night. The female lays hundreds of eggs at once.
"The potential for causing damage is huge," Kenian FAO representative Alessio Colussi warned.
The greatest danger involves swarms of moths tackling young corn plantings. Those have not yet developed any resiliance and can easily be completely destroyed. And the caterpillar does not only eat corn. It can also survive on another 80 plant species, including rice, tomatoes, soy, spinach, cotton, wheat, sugar cane, sorghum and millet.
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The Autumn armyworms: Dangerous caterpillars
The autumn worm isn't really a worm, but a caterpillar. When it's fed enough it turns into a moth which can cause catastrophic damage to crops in southern and eastern Africa.
Image: Lyle J. Buss/University of Florida/Bugwood.org
The autumn worm
The small caterpillar - no bigger than four centimeters - is not as harmless as it looks here. When thousands of these small pests fall into a field, the harvest is quickly destroyed. The wandering pests gnaw across the whole country.
Image: picture-alliance /dpa/CABI
The enormous corn eater
Spodoptera frugiperda (that is the name of the army worm in Latin) likes corn. He eats the leaves, but above all he bites through the inside of the plant. Corn is the most important nutrient supplier, especially in the south of the African continent. The FAO estimates that the pest can destroy more than three-quarters of a crop.
Image: Phil Sloderbeck/Kansas State University/Bugwood.org
Attack! Eat with military strategy
These spot-camouflage caterpillars crawl from field to field as if they're marching in to battle - that's why they are called "armyworms." In huge numbers they march from grasslands on to crops, where they eat everything in sight.
Image: gemeinfrei
Growing up in stages
On their way to adulthood, the seemingly never-ending caterpillars pass through six stages: from the tiny, transparent larvae to the almost four centimeters long moths. If they grow up, they pupate - the process of becoming a moth - just under the surface of the ground.
Image: Natalie Hummel/Louisiana State University AgCenter/Bugwood.org
From caterpillar to moth
After three weeks of feasting on crops and grass, the transformation begins. Then we see the metamorphosis to the "Noctuidae" - an owl-like butterfly.
Image: Mark Dreiling/Bugwood.org
Wings up and read to go!
And this is how the creature looks in all its splendor. With a wingspan of just under four centimeters, the nocturnal moths provide fast and efficient offspring - with females laying up to 1000 eggs in their lifetime. With no frost in the African climate you could find up to 12 generations in just a single year.
Image: Lyle J. Buss/University of Florida/Bugwood.org
Problems across Africa
Small, light and greedy: The moths can spread quickly over hundreds of kilometers in favorable winds throughout the continent. At the beginning of 2016, the Autumn armyworm was first detected in Nigeria, a year later it was already flying about 5000 kilometers further south. Europe is by no means too far away, experts warn.
On a journey around the world
The United Nations is already warning of a new crawler plague across Africa. "Pests do not know any national borders," says the UN Organization for Food and Agriculture (FAO). Originally, the butterfly species originates from the tropical regions of the American continent. From there they were towed to Africa.
Image: CC by Andy Reago & Chrissy McClarren
Limited solutions
Resistant Plants, Sand, or Chemistry: Farmers in North and South America have tested many compounds against creeping armyworms. It is best to fight the pest with pesticides, but some have already shown resistances. Experts suggest to dig trenches around the affected field. That way the caterpillars can be easily killed when they try to reach the neighboring field.
