A field trial was tarried out to study the combined effect of day maximum temperature. relative humidity on the corresponding number of captured Pectlnephora gossypleffa (Saunders) male moths as indicated by sex trap and the infestation in green cotton bolls in field. This study was conducted at Assiut and Gharbla Governorates throughout 2000 cotton growing season. The number of captured male moths was recorded each three days during the season. The relationship between day maximum temperature and the corresponding number of male moths captured in the traps was es­timated during spring revealed that number of moths increased gradually, thus forming a peak when day maximum temperature ranged between 36^°C on 5th May at Assiut and 33^°C on 20th May at Gharbla. The correlation value yielded a significant and positive 'r' value between day maximum temperature and number of trapped moths in trap and insignificant positive correlation between mini­mum temperature, minimum relative humidity and number of cap­tured moths during the valuable occurrence of green bolls sus­ceptible to infestation (three weeks old). The same trend was obtained, Le. insignificant positive cor­relation between temperature degrees and activity of newly hatched larvae which attack the green bolls In cotton fields, the average temperature fluctuated between 29^°C & 30^°C at both Gov­ernorates: Ghafbia and Assiut, respectively. The study also revealed that there is a relationship be­tween average relative humidity and the corresponding average number of newly hatched larvae of pink bollworm inside the green bolls and Insignificant positive correlation for Assiut Governorate (R.H. between 39 % and 46 %). A significant positive correlation for Gharbla governorate (R.H. between 66 % and 73 %) was found suit. able for activity of newly hatched larvae.