Return of the ‘killer slug’
12:56 22 April 2013
Copyright: Archant 2013
A new generation of “killer slugs” has emerged in Norfolk’s gardens, prompted by the warmer spring temperatures.
The UK’s first sighting of the voracious and cannabilistic Spanish slug was confirmed last year by Dr Ian Bedford, head of entomology at the John Innes Centre (JIC), after the creatures appeared in large numbers and destroyed his vegetable patch.
Now the Norwich scientist has found their offspring in his back yard in Cringleford – this time, devouring his spring daffodils.
Dr Bedford said although the adults would have perished in freezing winter, the arrival of warmer weather had enabled their buried eggs to hatch, with the hungry juveniles now about 5mm long.
He has collected these specimens for study at his laboratory in Colney as part of a research project to find out more about the pest and its ability to destroy valuable crops and vegetables.
Dr Bedford said: “Since we had all the publicity we had quite a few people contact us who were collecting up to 4,000 slugs a month in their gardens.
“We are not saying put loads and loads of slug pellets down to get rid of them, because of the environmental impact. I have found the most effective method is to collect them by hand and put them in a bucket of salty water, with some detergent in it to break the surface tension and make them sink.
“These slugs have some pretty unsavoury feeding habits and can carry germs, so it is best to sterilise the bucket afterwards with some household bleach, and wash your hands.”
Dr Bedford said the slugs’ unusual diet includes dead animals – including other slugs – fledgling chicks fallen from nests and even dog mess. He said the juveniles usually feed at night and retreat underground when the sun rises.
“We think because they have evolved on the Iberian peninsular where it is very warm, they don’t survive very well in winter unless they are protected from the frost,” he said.
“They can be quite difficult to identify, but the main factor is the unusual feeding behaviour and the huge numbers you can find them in. This is the first time I have ever seen my daffodils covered in baby slugs.”
The Spanish slug, an invasive species which can grow up to 15cm long, is usually brown or reddish brown, but last year Dr Bedford found specimens which were orange, yellow or black.
Dr Bedford is applying for grants to further his research of the species and he hopes to use genetic analysis to understand whether the Spanish slug is breeding with indigenous creatures. He has asked for the public’s help to report large populations of slugs on gardens, farms or vegetable patches.
Dr Bedford can be contacted by emailing firstname.lastname@example.org or via Twitter: @drianbedford.