Caterpillar plague wreaks havoc in Liberia

West Africa regional emergency threatened

22 January 2009, Rome - Huge hordes of ravenous caterpillars have appeared in northern Liberia, destroying crops and vegetation, sending terrified villagers fleeing from their homes, and raising the spectre of a food, health and environmental emergency in West Africa.

FAO Representative in Liberia Winfred Hammond, an entomologist, described the situation in Liberia as a national emergency and said unless the invasion was quickly contained it was "very likely" to escalate into a regional crisis involving neighbouring Guinea, Sierra Leone and Cöte d'Ivoire.

The two- to three-cm-long caterpillars, described by villagers as "black, creeping and hairy", are advancing in the tens of millions, devouring all plants and food crops in their path and in some cases overrunning homes and buildings. They pose a major threat to the already precarious food security situation in Liberia and the sub-region.

In some communities villagers are unable to reach their farms, because these are completely surrounded by the pests.

African armyworms?

Some 46 villages in Bong, Lofa and Gbarpolu counties of northern Liberia are confirmed to have been affected, including two-thirds of the 200 000 inhabitants in Bong County, the worst-hit area. There are reports that the caterpillars, suspected to be African armyworms (Spodoptera spp) are currently advancing across the border with Guinea.

The situation is made worse by the fact that many wells and waterways in the area are unfit for human consumption because of the huge volume of faeces dropped by the caterpillars. Also making things difficult is that much of the infested area cannot be reached by car so that the extent of the infestation has yet to be precisely determined.

FAO has assembled a task force including experts from Ghana and Sierra Leone to assess the situation, prepare an immediate action plan and devise medium and long-term measures, Hammond said. Specimens of the caterpillars have been flown to Accra to be identified exactly so that the most appropriate form of pesticide can be determined.

Liberia has set up three emergency committees to provide planning, resources mobilization and communication and information. The country lacks the financial resources and technical expertise to combat the emergency on its own and will require international assistance, Hammond said.

But he cautioned against the use of aerial spraying since it was likely to further contaminate the already precarious water supply in the area. And whatever the method, FAO recommends the use of less risky pesticides, including bio-pesticides when they are effective.

Giant trees

However, areas that have been hand-sprayed with pesticides have quickly been re-infested. This is because many of the caterpillars dwell on the leaves of giant forest trees such as the Dahoma, which can rise more than eight metres above ground.

The infestation is spreading fast because the pests are multiplying rapidly and adult moths can fly long distances under cover of darkness.

The plague is being described as Liberia's worst in 30 years. The last African armyworm outbreak in the sub-region occurred in Ghana in 2006.

Photo: Liberian Ministry of Agriculture
Rampaging caterpillars, Liberia.