A new pest?

Here’s a mystery – four of these slugs (see pictures) turned up on our back doorstep a few days ago and they appear to be Black Slugs, also known as Black Arion, Arion ater, although at about 3.5cm long, they were considerably smaller than the reported size at maturity of up to 15cm, or even longer! The mystery is: how did they get there?

They are an introduced species native to Europe and, according to Museums Victoria, as recently as 2009 they were not considered to be established in Australia. However, since then they seem to have popped up, sometimes in large numbers, in various places in Victoria and around Sydney and Adelaide. The Atlas of Living Australia has 29 records on its data base.

The Black Slug has no natural predators in Australia and has the potential to be a highly invasive pest. They can reproduce rapidly under favourable conditions. They are hermaphrodites and each partner in a mating pair can produce fertile eggs, up to 150 in a clutch.

In the UK, this slug is considered either as a garden pest or as an important component of woodland ground fauna, depending on what perspective is taken. Its omnivorous diet includes leaves, stems, dead animal or plant matter, earthworms and fungi. Its effect on our natural environment is unknown, but it does present a risk to seedlings and crops.

We would be interested to hear of any other local sightings of this slug. If you do find one, be aware that the slime should be avoided – use gloves when disposing of it.

Since we haven’t imported any garden soil or pot plants recently, the mystery remains as to how they arrived!