There are more than thirty species of slug in the UK, and April is the time when they start to multiply. The warm weather we get this month, coupled with the April rain showers create a paradise for them. If you turn over stones and logs you can often find their pearly looking eggs which are about 2 to 3mm across.
Whatever you may think of slugs, they do come in an amazing array of shapes and colours. Despite their awful public image it's really only a few species which misbehave and cause damage to garden plants and vegetables. Most slugs prefer a diet of dead vegetation and fungus and shun gardens in preference of the more damp conditions found in woodlands. Many of the species we find in our gardens today were introduced... by gardeners.
Some species, like the Maug's Slug (Testacella maugei) and the Shelled Slug (Testacella haliotidea), both of which have a tiny shell on their backs, are carnivorous, feeding on a diet of earthworms. They're also quite rare. Incidentally some slugs have an internal shell.
Slugs are also hermaphrodites, having both female and male reproductive organs. When mating, both slugs pass sperm to each other, and a few days later, both slugs lay their eggs in the ground. They may not be cute but they're... well... interesting.
Many gardeners regard all slugs as pests, and reach for the slug pellets at the first sign of leaf damage. Rather than spreading a heap of poison around the garden a better and cheaper option is to view slugs as free food for foraging wildlife. Hedgehogs, thrushes, slow-worms, frogs and toads will all enjoy a slug snack, and it's a much more natural method of slug control.