Greenhouse millipede

The greenhouse millipede (Oxidus gracilis) is a member of the class Diplopoda, belonging to the order Polydesmida. It is a small, segmented arthropod characterized by its brownish color and ability to secrete cyanide compounds when threatened, which serves as a potent chemical defense against predators and makes it a persistent nuisance in controlled environments.

This pest thrives in warm, humid conditions, making greenhouses, indoor nurseries, and botanical gardens its primary habitats. It is polyphagous, capable of feeding on a diverse range of plant species, although it poses the greatest threat to tender seedlings, young transplants, and plants with succulent roots that require consistently moist soil.

The life cycle of the greenhouse millipede is fundamentally soil-dependent. Females deposit eggs in clusters within the soil profile or moist organic debris. Following hatching, the nymphs undergo several molts, gradually increasing in size and segment count. Because they spend their entire development underground or hidden beneath debris, they often go unnoticed until significant population levels are reached.

The damage caused by Oxidus gracilis is primarily focused on the root systems and the root collar of plants. By grazing on young, fragile tissues, they disrupt nutrient uptake and create entry points for soil-borne pathogens, leading to stunted growth, yellowing, and eventual plant mortality. High populations can devastate entire benches of greenhouse transplants very rapidly.

Effective management strategies require a combination of preventative and curative measures. It is essential to maintain proper hygiene by removing decaying organic matter and ensuring that pots or benches have adequate drainage to prevent excessive moisture. Chemical control involves the application of soil-drenching insecticides registered for greenhouse use, while biological controls, such as entomopathogenic nematodes, offer a targeted solution for suppression.