Black Keeled Slugs
This species of slug is rarely seen,due to it spending much of its time underground attacking root crops,in particular potatoes, where they tunnel into the tubers.
They can sometimes be found feeding above ground, and are also known to attack flowering bulbs such as tulips.
Breeding takes place in autumn and early winter and the eggs lie dormant in the soil until spring.
Mature slugs can grow up to 100mm (4”) in length.
Damage takes place in late summer and autumn when they make round holes in the skin, and form cavities within the tubers.
This becomes progressively worse the longer the crop is left in the ground, to limit the damage, lift the potatoes as soon as the tubers have matured.
These pests are difficult to control, because they spend much of their time below soil level, only coming to the surface in warm weather and after heavy rain.
Often by the time the potatoes are lifted the slugs have gone back into the soil.
The use of slug killing products such as pellets, liquid slug killer, and/or nematodes at these times will reduce their numbers.
Some varieties of potato are less susceptible to damage, so purchasing such varieties can alleviate the problem.