This study was conducted under field conditions at Quessna district, Monufya Governorate during two successive seasons 2009 and 2010. The present work aimed to throw light on the effect of climatic factors temperature degree  and relative humidity on land snails population and their damage to some stand crops( Clover, Lettuce and Navel orange ).   The obtained results could be summarized as follows:- 1)- Monacha cartusiana (Muller) and Eobania vermiculata (Muller)  were only observed  infesting Clover, Lettuce and Navel orange during the experimental period.  Also, the the ecological studies indicated that M. cartusiana was found in abundance on Clover and Lettuce both, meanwhile Navel orange had E. vemiculata more than the another, snail. 2) - Clover was the most attractive to M. cartusiana followed by Lettuce and Navel orange, whereas, the last crop  was the most attractive to E. vermaculata than Clover and Lettuce. 3)-  The land snails population was fluctuated during the experimental  crop life from month to month  due to    variations in  temperature degree and relative humidity. The results indicate that there is a positive  correlation between snail population and the relative humidity , meanwhile it is negative with the temperature degree. The highest population (115.5 individuals) was recorded in February (16 C &59.9 % R.H.) and the lowest one (33 individuals) in May (29 C & 54.7% R.H.). 4)-  The obtained results showed  that the highest infestation of land snails (0.89%, 0.83% and 0.64%) and the lowest (0.45%, 0.49% and 0.19%)   for Clover, Lettuce and Navel orange were recorded  in March (18.6C & 59.7% R.H.)and in May (29 C & 54.7% R.H.), respectively. 5)- The obtained results proved that the most suitable geographical conditions to increase the population of land snails are low temperature degree and height relative humidity. Also, it is added that, there is a  positive correlation between population of land snails and their damage to the three tested crops.