Back It captures live prey, which it feeds on. Clean-up predator: A mono- or oligophagous predator, i.e. more or less specific; it appears when prey density is very high and leaves the vineyard when the prey disappears. Protective predators: they are visible at low prey densities and are present on crops all year round. They are generally polyphagous predators with limited food requirements and relatively modest reproduction rates. Their numbers follow the changes in the numbers of their prey.