Pests: find out more SLUGS

Slugs  damage a wide range of container grown and outdoor crops.   They are generalist feeders with a preference for young shoots and leaves.  They eat seeds, leaves, stems, flowers and roots leaving large irregular holes.  Feeding damage is easily seen causing direct crop losses as well as downgrading.   Damage soon after planting can result in complete crop loss.  Damage can promote fungal growth while holes, slime and faeces can reduce the value.

The most common species in glasshouses are the slug Deroceras panormitanum and the snail Oxyloma pfeifferi. Deroceras panormitanum  is a small brownish slug, up to 3.5 cm long. Oxyloma pfeifferi adults are 9-12 mm long with brown to black shells.  Derocerus reticulatum (the grey field slug) and Arion hortensis (the garden slug) are most common outdoors.

Slugs and snails are most active at night, but will feed during the day under favourable conditions.  They require damp, humid conditions, preferring dense foliage at temperatures between 18°C and 30°C.  In hot, dry conditions they shelter in groups in damp places.

Slug eggs

Slug
 

Slugs are hermaphrodite and do not need to mate, although they usually do.  They lay eggs up to three times a year in piles of 5-50 with a maximum of 500 eggs per year.  Eggs are protected in a tough shell and can be spread around glasshouses through irrigation systems, however they are susceptible to desiccation and frost.  Hatching takes between 3 weeks in a warm spring and several months in autumn.

Young slugs are similar to adults and feeding starts soon after egg hatch.  Outdoors, snails and slugs usually over-winter in groups.  Under glass,  D. panormitanum can be found at any time if temperature and humidity conditions are suitable.  O.pfeifferi is active between late spring and autumn and hibernates over the winter on the sides of pots and trays.  Adult slugs and snails can live for several months or several years.