Biological control refers to beneficial insects, mites and spiders that eat invertebrate pests. In general beneficial species are naturally occurring and can be found wherever there is a suitable food source and a suitable habitat. An IPM strategy takes advantage of beneficial species by making sure that they are not disrupted by the use of pesticides and that farm management practices allow the crop to become a suitable place for them to live.
Both pest and beneficial invertebrates can be divided into two categories, transient and resident. Transient refers to species that move into the crop from outside the farm. This often happens in spring and autumn which are peak times for many species to become active. Some examples of transient beneficial species are ladybirds, brown lacewings and hoverflies. Some transient pests are Diamondback moth, Heliothis and Rutherglen bugs. Resident species are invertebrates that are often found in the soil and live year-round on the farm. Examples include species such as predatory ground beetles, predatory soil mites as well as pests such as slugs, snails and earwigs.
Some beneficial species are commercially available and are released into crops when naturally occurring species are not enough on their own. They are more commonly used in protected cropping and some outdoor crops such as strawberries, macadamias and citrus than in vegetable production.