The timing and duration of exposure to herbivore kairomones (mucus from the snail <i>Helix aspersa</i>) determines the degree to which plants are attacked by snails.

<p>Early exposure of <i>Brassica nigra</i> seeds to snail mucus and deionized water did not lead to differences in herbivory by snails compared to seeds that received early exposure to only deionized water. However, plants that received repeated exposure to snail mucus and deionized water (five exposure events over the course of growth) experienced lowered rates of snail herbivory compared to seedlings that received repeated exposure to only water, regardless of early exposure as a seed. Data represent means ±1 S.E. of main effects for non-transformed data (statistical analyses in text use logit-transformed data).