Greenhouse slug

Systematic position: The greenhouse slug (Milax gagates) belongs to the phylum Mollusca, class Gastropoda, order Stylommatophora, and the family Milacidae. It is a significant pest of both agricultural crops and ornamental plants, commonly found in temperate regions and greenhouses worldwide.

Biology and life cycle: This slug species typically measures 40–70 mm in length and possesses a dark grey to black body with a distinct keel running along the back. Being a hermaphrodite, it reproduces throughout the year in favorable conditions. Eggs are laid in clusters in moist soil or under organic debris. The development rate is highly dependent on humidity and temperature, with populations peaking during cool and wet seasons.

Nature of damage and pest significance: The greenhouse slug is nocturnal, remaining underground or hidden under debris during the day. It feeds by scraping and chewing plant tissues. Its feeding activity results in deep holes in roots, tubers, and the base of stalks. Beyond direct feeding damage, it creates entry points for various phytopathogens, causing rot and significantly reducing both yield and the shelf life of produce.

Host plants: Milax gagates has a wide range of hosts. It is particularly destructive to potatoes, carrots, beets, and other root vegetables. Additionally, it causes severe damage to young seedlings, cabbage, and various nursery crops. In greenhouses and commercial farms, high infestation rates can lead to the total destruction of young plant populations.

Protection measures: Effective management requires an integrated pest management (IPM) strategy:

• Implementing deep tillage to destroy subterranean burrows and expose slug eggs to desiccation.
• Removing vegetation debris and weeds to eliminate breeding sites and hiding places.
• Applying granular molluscicides containing metaldehyde or iron phosphate around high-value crops.
• Creating physical barriers like crushed gravel or wood ash that hinder slug movement.
• Maintaining soil structure to improve drainage and prevent waterlogging, which favors slug survival.