Around two weeks ago, the U.N. Food and Agriculture Organisation (FAO) first raised the alarm that a caterpillar infestation in Liberia could turn into a regional emergency affecting other countries in West Africa.

Initially the insects were suspected to be highly destructive army worms, which bore up to 5 cm (2 inches) into the ground to pupate before turning into moths that can fly as far as 1,000 km (620 miles).

The government declared a national emergency and the invading caterpillars are thought to have affected the crops and houses of some half a million people.

On Jan. 29, the FAO issued a second press release saying it was leading a team of international experts "racing against time to contain a vast plague of voracious army worm caterpillars", to prevent them spreading across the region. At that stage, the U.N. agency seemed pretty certain of their identity.

But on Tuesday it emerged the insects were not army worms after all but of the Achaea catocaloides species. Like army worms, they too eat vegetation, including cocoa trees, which could be a threat to plantations in West Africa if the conditions remain conducive for reproduction, the scientist who identified the pests told Reuters.

The caterpillars have spread to Guinea and could be a threat to farmers in neighbouring Ivory Coast, which is the world's top cocoa grower.

Yet in a press release on Wednesday, the FAO appeared to water down its warning of a dire regional emergency, saying the threat of future outbreaks could be contained more easily than thought.

It said a key difference between the two types of insect is that those now rampaging across Liberia actually spin their cocoons on the ground under fallen leaves. As a result, they are less difficult to destroy than army worms and their spread can be limited.

The FAO said its team in the field had seen villagers stamping on the cocoons, and collecting and burning them, although this couldn't entirely stop them spreading.

Also on the positive side, while the caterpillars have polluted water supplies and damaged some crops like coffee, cocoa, plantain and bananas, the FAO said staple food crops - including maize, rice, sorghum and millet - have generally been spared. That's likely to ease fears of the infestation causing a widespread food emergency.

Nonetheless, the FAO warned the government isn't prepared for further outbreaks, and said the current infestation offered an opportunity to develop a better response system against pests.

AlertNet can't help wondering whether the FAO might be feeling a little embarrassed that it jumped on the army worm bandwagon a little too soon, and put out a rather alarmist message in the early days of the outbreak.

In Wednesday's statement, the U.N. agency said the international field team in which its scientists participated had established that "the insects were not army worms, as had been reported, but larvae of another moth species".

That rather fudges the FAO's own assertion last week that the insects were indeed army worms.

In its Jan. 29 press release, it noted the insects were behaving in a way that was atypical of army worms by living in tall trees, but said its permanent representative in Liberia, Winfred Hammond, was sure that's what they were.

"In fact, he initially doubted they could be army worms, one of the most destructive of insect pests, but positively identified them as such in tests last week," read the release. Not only this but it added the caterpillars had been burrowing into the ground and devouring all vegetation in their path.

That information is at odds with what's presented in the latest FAO press release. Perhaps some kind of explanation is in order?

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