In order to attract beneficial insect, it is important to understand the role of Argentine ants in your garden. Many damaging insects such as aphids, mealybugs, scale produce a sweet substance called “honeydew” which the ants like. In return, the ants protect them from their enemies and often move them to new locations to increase their populations. Controlling ants in your garden will usually solve many if not most of your insect problems.
You can encourage beneficial insects into your garden by planting flowers such as alyssum, yarrow, cilantro, cosmos, marigold, dill and thyme.
Source:
http://ipm.ucanr.edu/QT/beneficialpredatorscard.html