Milax gagates, known by the common name greenhouse slug, is a species of air-breathing, keeled, land slug, a shell-less terrestrial gastropod mollusc in the family Milacidae.
The native range of Milax gagates was originally from Morocco through Tunisia and southern Spain to southern France and the Balearic Islands.
It is an endangered species in Rhineland-Palatinate, Germany.
The species may be native to the Canary Islands.
Milax gagates has been introduced in the area between Portugal and Galicia, the Atlantic coastlands of France to Belgium, the British Isles, and in many other areas almost worldwide (Australia, Tasmania, New Zealand, Japan, Pacific islands, South Africa, Atlantic islands).
Milax gagates lives mostly in cultivated areas, often the coast, and also in forests, shrublands, and natural meadows. It prefers habitats close to water. It hides under stones, moist ground litter and in soil cavities.
It feeds on fresh herbs, including the roots. It can sometimes be a pest of crops such as carrots and potatoes. It is occasionally damaging to gardens and crops in Britain. It is an agricultural pest on soybean, sunflower, and oilseed rape in Argentina.
In Britain copulation takes place during the period from spring to autumn. During copulation both slugs cling together so closely that no everted genitalia are visible. Under laboratory conditions, the first eggs are laid 5–15 days after copulation. At one time approximately 15 eggs are laid. This can be repeated several times, but in total not more than 100 eggs are laid by one individual. The dimensions of the eggs are 2 × 1.5 mm.Self-fertilization is also possible.
The slug is semelparous, dying 15 to 30 days after laying eggs. Juveniles hatch after at least 25 to 30 days. Maturity is reached in 4 to 5 months under laboratory conditions.
