Tandonia budapestensis

Biological Name

Tandonia budapestensis (Hazay, 1880)

Common Name

Budapest slug

Other Common Names

Keeled slug


A medium-sized keeled slug, very slender when extended and 50 to 60 mm long. The pneumostome is located in the posterior half of the mantle. Its colour is black-brown with a dirty-yellow stripe along the keel. The prominent keel reaches the mantle. The sole has a dark central and paler lateral areas.

Other Similar Species

Milax gagates

Biological Notes

The budapest slug has an annual life cycle, eggs, juveniles and adults pass the winter. It is a sub-surface species with burying ability.

Geographic Distribution

Its native range is Eastern Europe, but it has spread to Central Europe and the British Isles, New Zealand and probably the USA.


The budapest slug lives in man made habitats, urban areas, gardens, ploughed fields, occurs in greenhouses and woods.

Crops at risk

Due to the subterranean life, the damages of the budapest slug are root crops, mainly potatoes and some ornamental plants in Western Europe.

Damage Caused/Symptoms

The slug eats holes in the surface of tubers and bulbs.

Impact and Severity

One of the most damaging species in the UK.

Prevention and Control

The slug-parasitic nematode Phasmarhabditis hermaphrodita is used as a biological control agent against the budapest slug.

Natural Predators

The budapest slug is a prey of several, field-inhabiting ground beetle species.