Insects and plants are affected by some weather factors all over the world. Experiments were carried-out to studying survey for lepidopteran-species and effect of temperature, relative-humidity and wind-velocity on population fluctuations of Spodoptera littoralis (Boisd) and Spodoptera exigua (Hubner), which attacking plants of evergreen, Paspalum vagenatum (Seashore Paspalum Turfgrass) in Smart-Village, Giza Governorate and Maryland-garden, Cairo Governorate during 2021 season to study population fluctuations of major and minor cotton leaf worms. Through the survey by using of light trap "Robinson type", five noctuid species (Agrotis ipsilon (Hufnagel), Agrotis segetum (Denis and Schiffermüller) S. littoralis, S. exigua and Spodoptera frugiperda (Smith) were recorded. Results showed that, the highest-population peaks of S. littoralis in Smart-Village were recorded in beginning of June and mid of October. While the highest population peaks of S. exigua in Smart-Village were in mid-April and mid-September. In Maryland-Garden, S. littoralis recorded two peaks of abundance in mid-June and mid-October, and S. exigua recorded two peaks in beginning of May and mid of September. Correlation coefficient values between independent factors (temperature, relative-humidity, wind-velocity) and populations of S. littoralis or/and S. exigua showed varied effects during the season. In general, S. exigua infestation was higher compared with S. littoralis in both areas during 2021 season, and populations of S. littoralis and S. exigua were higher in Smart-Village than Maryland-Garden.