Entomopathogenic nematodes of the genera Heterorhabditis and Steinernema are used as an insect biological control in agriculture. Numerous new species are being described but generally little information is provided on their ecological or physiological information. Therefore, this paper presents examination of virulence, penetration rate, reproduction, and some energy reserves (total lipids, total proteins and total carbohydrates) for six species of entomopathogenic nematodes, 3 species of Heterorhabditids ((HP2), (HP4) and H. indica) and 3 species of Steinernema ((S3), S. riobrave and S. rarum) are extracted from soil samples at different countries and places to refer the superlative one to unfavorable environmental conditions. The tested species differed in their penetration rate to Galeria mellonella larvae. Heterorhabditis sp. (HP2) recorded the highest penetration rate (56 %) where it recorded highest total lipids (35.8 %), highest total proteins (60.3%) and the highest virulence to G. mellonella (25%). The highest total carbohydrates were recorded to the steinernema   rarum (26%) while the highest reproduction was recorded to Heterorhabditis indicus (149914 IJs/larva).