There are many different forms of companion planting which can be beneficial in managing pests in an organic garden. Trap crops are one type of companion plant which can be an important part of integrated pest management.
Trap crops are plants which are placed alongside, around or between the plants which you wish to protect. These plants attract certain pest species, which are often drawn to them preferentially. They therefore distract the pests in question and make it less likely that an infestation will occur on your main crops.
The plants may be semi-sacrificial, plants which grow quickly enough or prolifically enough that you do not really mind losing a few. Or they may be sturdy enough to withstand a certain level of infestation, and remain in place. If they remain in place, the congregations of pests on them can be managed manually. But they will also entice in natural predators from the surroundings which will often deal with the problem for you.
In a recent article in Treehugger, I talked about just a few of the trap crops which I believe have been helpful in my own garden:
Trap Crops I Like To Use in My Garden
These are, of course, just a few examples. The trap crops which work best for you will likely vary, since both the conditions and the pests will be different from one location to the next. But the plants I mention in this article can be beneficial in a range of geographical locales.
If you are interested in a design for your own garden to help you manage pests in an organic way, please do get in touch to discuss your requirements.