The ecosystem in an organic garden needs certain elements to be successful and one of them is beneficial plants called insectary plants.
 

They help introduce predatory insects into the garden to aid in pest control.
Insectary plants in a garden promote the pollen and nectar resources for natural predatory insects that attack the unwanted and harmful pests.

The insects you want to promote are
Lady Beetles                                Bees
Hover flies                                  Beetles
and Parasitic wasps
 
As well as animals like
Frogs,
Lizards,
Birds and spiders.

The type of plants that promote such life and diversity in the garden are plants like
Yarrow                                         European Dandelion 
Queen Anne lace                             Elderberry
rue                                               Rosemary
Dill                                               coriander
Nasturtium                                     Mizuna
angelica                                         Flowers
Thyme                                           Citrus trees
Veggies such as Broccoli that have been allowed to go to seed.
Even weeds like Thistle that attract aphid can be a great food supply that will promote more beneficial insects once the flowers of the Thistle open.
It's all about diversity and balance that nature has provided since before man.
To be truthful, man has for most of the time created more problems with the constant use of Pesticides, herbicides, GMO and especially with the balance that nature has been promoting since day dot.