The population dynamics of teak defoliator, Hyblaca puera was studied on three commercial teak plantations in South India. Defoliator, H. puera occurred in two distinct epidemic infestations in all the sites, one during April-June and the second during September-December. The correlation between larval population and weather parameters showed that rainfall had highly significant positive influence and wind velocity had negative influence on larval population. Other factors like relative humidity, minimum and maximum temperatures were of no significance.