Nature Features

Conservationists and gardeners fear 'killer slugs'

By Lennart Simonsson Jul 13, 2007, 12:24 GMT

Copenhagen/Stockholm - A species of slugs that gobble up vegetables, flowers and other plants has grabbed headlines in the Nordic region in recent weeks.

On Friday, the Danish Society for Nature Conservation urged authorities to take on the Spanish slug, also known as Arion lusitanicus, citing that the species is not indigenous to Denmark and should be eradicated.

Related to the black slug, the Spanish slug that hails from the Iberian peninsula has few enemies in the Nordic countries.

The species is believed to have arrived some 20 years ago, likely with plant shipments, and has since spread.

A relatively warm and wet spring season this year has provided ideal circumstances for the slugs that have become a plague.

Dubbed the 'killer slug' because it eats dead members of the same species, the slug can grow to some 12-15 centimetres in length and has become a pest for many home owners, but has also spread to parks, recreational areas and farms.

Experts estimate that a single slug, which is a hermaphrodite - meaning that is has both male and female reproductive systems, can lay some 400 eggs, and start an infestation.

'When an animal eats the killer slug it gets its mouth full of thick slime and spits it out again,' Ted von Proschwitz of the Gothenburg Natural History Museum in Sweden said.

Reports suggest that home owners in Sweden have begun to smuggle pesticides from neighbouring Denmark and Germany in an attempt to eradicate the slugs.

Von Proschwitz said that there were risks with trying to poison the slugs, as other slugs, snails and frogs risked being killed.

Newspapers and authorities are offering tips on how to protect garden lots, including not having open compost heaps.

Cutting off the slug's head with a spade or scissors, and collecting and pouring boiling water over the slimy creatures were among recommended methods to kill the slugs.

Placing bowls of pet food or salad leaves in the garden to catch the slugs is a frequent suggestion. Beer also seems to attract the slugs.

A couple in Norway were happy to tell news media that they had experimented with various strengths of beer and were pleased to note that they caught the most slugs in bowls filled with low-alcohol beer - 'cheaper' and 'not a waste of good beer,' the couple said.

Swedish Agriculture Minister Eskil Erlandsson said he had no good advice when recently approached by farmers worried that the slugs could be collected with hay and fodder for cows, potentially fermenting in the bales.

In Denmark, the conservationists said authorities should introduce 'massive, coordinated, national measures' against the slugs.

Christian Wedell-Neergaard, environment spokesman of the Conservative Party, junior partner in the minority Danish government, said Friday that there was need to act against the 'threat' the slugs pose 'to Danish nature.'