First found in the Americas, Sena, or spodoptera frugiperda, was then reported from Africa in 2016 and India in early this year.
It has already caused extensive damage to maize cultivation and is affecting sugarcane, paddy and vegetables and fruits as well.
Measures to prevent its spreading include destroying the caterpillar individually, using pesticides and using less nitrogen-based fertilizer and diversifying crops.
12 pesticides recommended temporarily
Registrar of pesticides J.A. Sumith says 12 pesticides still on experimental level have been introduced on temporary recommendation to curb the menace.
Farmers could obtain related advice from agricultural officers or by calling hotline 1920.
Convener of the Sri Lanka Agrarian Conference Namal Karunaratne alleges the caterpillar had been introduced by multinational companies through maize seeds to destroy local crops.