This experiment was conducted in tomato field at Agriculture and Forestry University (AFU, Chitwan, Nepal) between October 2016 and May 2017 to evaluate effect of net house on invasive insect species of tomato moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). The trial was setup with two treatments inside net house and under open conditions and was designed with four replications. The adults of T. absoluta were observed significantly lower numbers inside the net house (1.41 adult/trap) compared to the open condition (24.84 adult/trap). The T. absoluta population increased with rainfall. The marketable yield was significantly higher inside the net house (100.91 ton/hec) due to reduction of damage to tomato fruit (4 ton/hec) by T. absoluta. The initial level of investment was found to be higher inside the net house when compared to open cultivation. In terms of economic analysis in long term aspect only, the net house is a suitable means of pest management against T. absoluta.