The 'beet cyst nematode' even undergoes a complicated development in the plant root, which is necessary for reproduction. As a result, it leaves behind very resistant cysts in the soil. The larvae contained in these remain viable for many years and are only stimulated to hatch by root excretions of the corresponding plants. While such nematodes are often highly specialized in individual plant species or families, free-living nematodes tend to cover a larger spectrum of plants that they can feed on themselves.