As it is known that the excessive use of pesticides causes many environmental problems, the effects of four aqueous plant extracts and their powders [Solanum nigrum L., Withania somnifera (L.) Dunal, Salix mucronata Thunb. and Lawsonia inermis L.] were evaluated as natural molluscicides on the land snail Monacha obstructa (Family: Hygromiidae) under laboratory conditions. Three different bioassay methods were used: contact, leaf-dipping and bait techniques. The results indicated that, using all methods, S. Nigrum extract was the most toxic extract for the terrestrial snail M. obstructa. The contact technique of the tested plant extracts was the most effective method of application compared to other methods. Moreover, using plant extracts was better than using powders of these plants for controlling the terrestrial snail M. obstructa. In addition, the results indicated that the aqueous extract of S. nigrum gave the highest percentage of reduction in the snail population when assessed under field conditions. The obtained data showed that plant extracts were significantly effective against the terrestrial snail and could be used as alternatives to pesticides in integrated pest management.