BAN NONG TOR, Thailand/SINGAPORE (Reuters) - Looking out at his empty, red-earth field, Thai farmer Puang Timdon said his two-week-old maize crop didn’t stand a chance against the fall armyworm pest.

“All the 8 rai (1.28 hectare) I planted were all heavily infested,” said the 42-year-old from his farm in Ban Nong Tor town in Pak Chong district, 180 km (120 miles) northeast of the capital Bangkok.

“The worm ate the whole field in three days, leaving so much damage that it wasn’t worth saving.”

Fall armyworm, a caterpillar that got the name because it invades croplands in droves, much like an army, has rapidly spread across Asia since it was detected in southern India late last year. Fields in Bangladesh, Myanmar, Vietnam, Indonesia and Taiwan have fallen victim. In Thailand, it has badly affected the country’s corn crop, much of which is sold to the animal feed industry.

In recent months, the pest has also been found in 18 of China’s 33 provinces and regions and is now threatening to spread across the key corn region in the northeast. China is the world’s second biggest corn consumer and producer.

“It is a major issue for crops. It could pose a food security threat,” said Phin Ziebell, an agribusiness economist at National Australia Bank. “Management cost is an issue for small farmers.”

Marjon Fredrix, an agricultural officer at the U.N. Food and Agriculture Organisation (FAO), said some countries have reported damage to crops hit by the pest at 1.2% to about 10%, while others had put the figure at 20% to 40%.

“Once the fall armyworm has arrived, it can’t be eradicated, and farmers will have to manage it,” Fredrix said.

A dip in the production of corn, largely used in Asia to feed animals, could force hog, poultry and cattle growers to rely on expensive imports and dent incomes of millions of small farmers.

The fall armyworm invasion comes against the backdrop of planting delays in the United States which lifted benchmark Chicago corn futures Cv1 by nearly a fifth last month.