Gardeners face alien slug plague
14 September 2012
Populations of non-native Spanish slugs (Arion spp,) are flourishing so successfully following this year's wet weather that they may be posing a serious threat to British species – with worrying consequences for gardeners.
Despite rumours of the recent arrival of a rampant new species, named as Arion flagellus, in fact there have been several strains of Arion present in the UK for decades including both A. flagellus and an even more invasive species, A. vulgaris.
Identification can be very difficult, and is further confused by their habit of breeding indiscriminately to produce hybrids. However, all are large and reproduce very quickly, laying up to 400 eggs in a year – four times more than the UK's 32 native species of slug.
There's now evidence that Spanish slugs have taken over at some sites, while other species have disappeared. A similar trend in northern Europe has seen a voracious hybrid of A. vulgaris causing serious problems for agriculture, made worse by the lack of natural predators which will tackle such a large slug.
'It's only a matter of time before we get this malign form coming into the country,' says entomologist Dr Gordon Port, of Newcastle University. 'And there's no easy way of controlling them: even biological controls don't do more than make them feel a bit poorly.'
The damp conditions this summer have proved ideal for slugs, with populations of all species said to have trebled in some areas and garden retailers B&Q reporting sales of slug pellets up by 74%.