This is the VOA Special English Agriculture Report.

Officials in Liberia say tens of millions of caterpillars are destroying crops and polluting waterways in the country's agricultural centers. 

The United Nations Food and Agriculture Organization says the caterpillars are invading houses in some areas. More than one hundred thousand people have fled their homes because of the insects.

The government in Monrovia has appealed for international help. Agriculture Minister Christopher Toe urged other countries to help save Liberia's crops and other vegetation that the caterpillars feed on.

The caterpillars are black and hairy and two to three centimeters long. They were first reported in Bong County in northern Liberia on January fifteenth. They have spread into areas of Lofa County and Gbarpolu County, bordering Guinea and Sierra Leone.

The area [bad word] by the caterpillars has some of the richest farmland in Liberia. The agriculture minister said Bong County grows most of the country’s cassava, eddoes, plantains, bananas and potatoes. 

Ben Donnie, an environmental activist, said the Liberian food supply is sure to suffer. He noted that Bong and Lofa counties produce the most rice, and he added, “We cannot live without rice.”  

As the caterpillars feed on crops, their waste pollutes waterways and drinking wells. 

The caterpillar invasion could be the country's worst in thirty years. Winfred Hammond is the U.N. Food and Agriculture Organization representative in Liberia. He says an unusually late rainy season might be causing the invasion. And unless it is quickly contained, he says, it could grow into a crisis involving Guinea, Sierra Leone and Ivory Coast. 

Workers are using hand-operated pumps to spray pesticides to kill the caterpillars, but others quickly return. And hand pumps cannot reach insects in tall trees. Many of the caterpillars live on the leaves of forest trees such as the Dahoma, which can rise more than eight meters. But the F.A.O. representative in Liberia warned about spraying pesticides from airplanes because of the risk of additional water pollution.

The caterpillars were suspected to be African armyworms -- so named because they look like an army on the march. And [bad word]  an insect expert at Michigan State University, says once they get to the marching point, they are difficult to stop.

And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. Transcripts, MP3s and podcasts of our reports are at [bad word]  I'm Jim Tedder.