The population dynamics of lepidopteron pests in cabbage was studied by recording the number of pests on five randomly selected plants from each plot during 2009- 2010. The lepidopteran pests recorded included cut worm (Agrotis ipsilon Hufner), cabbage leaf webber (Crocidolomia binotalis Zeller), DBM (Plutella Ayllostella), tobacco caterpillar (Spodoplera litura F), imported cabbage worm (Pieris rapae), cabbage butterfly (Pieris brassicae Linnaeus) and cabbage looper (Plusia orichalcea). Out of these, cabbage butterfly and cut worms were the major pests causing maximum damage. The natural enemies recorded were Apanteles (Cofesia) spp. and Hyposofer ebeninus (Grav.) Cut worms were first noticed in the first week of November, 2009 and reached its peak in the first week of December whereas DBM and tobacco caterpillar were first seen during the second week of November. 2009. Imported cabbage worm and cabbage leaf webber were observed during the third week of November, 2009 whereas; cabbage looper was first noticed in the fourth week of November, 2009. Cabbage butterfly first occured in the last week of January and the highest population was observed during the second week of February. It was also observed that weather parameters did not influenced the pest's population build up during the entire crop period. The evaluation of efficacy of the different eco friendly insecticides against Pieris brassicae indicated that endosulfan was the most effective but at par with botanicals, annonin and microbial, spinosad. It was also recorded that Beauveria bassi ana and azadirachtin were safe to the natural enemies as compared to spinosad which reduced the population of natural enemies.