A total of 345 soil samples from rubber growing areas were collected from ten districts of Kerala to find out the natural occurrence of entomopathogenic nematodes (EPN). Bioassay of samples was conducted by soil baiting technique using fifth instar larvae of greater wax moth, Galleria mellonella, under the laboratory condition. Seventy three samples (21%) yielded EPN, among these 61 samples (18%) collected from Thiruvananthapuram, Kottayam, Thrissur, Palakkad, Kozhikode and Malappuram regions yielded both Heterorhabditis and Steinernema spp. Twelve soil samples (3%) collected from Kollam, Pathanamthitta, Ernakulam and Idukki regions showed the presence of Heterorhabditis sp. alone. Laboratory and field evaluation of EPN against bark feeding caterpillar, Aetherastis circulata infesting rubber plants was conducted. The results of the laboratory study showed 84 per cent mortality of second instar larvae of A. circulata within 24 h followed by 88 and 92 per cent mortality of third and fourth instar larvae, respectively when they were inoculated with EPN @ 320 ijls/5 larvae. Hundred per cent mortality was recorded at 48 h of exposure. The multiplication rate was found to be reduced at lower as well as higher inoculum levels. No significant effect was noticed upon the field application of EPN against A. circulata.