Companion planting can help to increase crop productivity through a variety of mechanisms, which may sometimes be combined. These include pollination, weed suppression, and pest control, including by providing habitat for beneficial insects. 
Companion planting can reduce insect damage to crops, whether by disrupting pests' ability to locate crops by sight, or by blocking pests physically; by attracting pests away from a target crop to a sacrificial trap crop; or by masking the odour of a crop, using aromatic companions that release volatile compounds. Other benefits, depending on the companion species used, include fixing nitrogen, attracting beneficial insects, suppressing weeds, reducing root-damaging nematode worms, and maintaining moisture in the soil.