The Martians have Landed …

2 minute read
Written by Dr Fi Draper PhD, MSc, CMIOSH, FIEMA, CEnv on Apr 22 2014

Ok, so that was a slight exaggeration. They’re Spanish Slugs not Martians, but they have landed and we have good reason to be concerned.

Slugs are composters - i.e. they break down vegetation. They are also a source of food for other wildlife. Most slugs live underground. According to SlugWatch, a typical UK garden is home to over 20, 000 slugs and an acre of farmland can support over 250, 000. We generally only notice significant numbers of slugs in cool, rainy or foggy conditions.

There are around 30 different species in the UK. Four of our native species are classified as pests due to the estimated £8 million worth of damage they do to vegetable crops each year.

The Spanish slug can survive many slug pellets and tolerate drier conditions that native slugs

The Spanish Slug (Arion vulgaris) is in a different class altogether. It was first identified in the UK in early 2012 by Dr Ian Bedford, Head of Entomology at the John Innes Centre, Norwich. It is believed that the slugs entered the UK on imported salad leaves, bare rooted trees or potted plants. Individuals vary in colour from bright orange to reddish brown. Full grown adults measure between 8cm to 15cm in length and produce approximately twice as many eggs as our native species.

Given its Mediterranean origins, the Spanish Slug is also much more tolerant of hot, dry conditions and has a significantly broader diet. This omnivore is quite happy to munch on excrement, dead animals and crops that native slugs normally ignore. They also produce huge amounts of mucus making them less appetising to predators and can survive eating many slug pellets.

During the winter many adult slugs, including Spanish Slugs, disappear underground or die but their eggs survive. As scientists are so concerned that the Spanish Slug will rapidly become a significant pest species, they would like members of the public to report sightings to them via the SlugWatch website.

Slug numbers start to increase in the Spring after the winter dormant period. So, if you fancy giving helping in this important, if unglamorous project, get looking under logs and plant pots. Further information, together with identification charts are available from SlugWatch.