Slugs and snails are hermaphrodites, which means they have both male and female sex organs. They lay their eggs in masses of up to 100 eggs in soil, under debris, rocks and plants. The eggs are large, 1/8 to 1/4 inch in diameter, and are white or colourless.The eggs take from two to four weeks to hatch but will not do so unless their is moisture present.
A single slug can lay up to 400 eggs in a year, and they start doing so at the tender age of three months. Slugs can live up to 2 years and the common brown garden snail may live in your garden for up to 12 years.