Tansy is a perennial, herbaceous flowering plant that is native to temperate Europe and Asia, though it has been introduced to other temperate climates, such as North America. It grows up to 150 cm tall and bears yellow button-like flowers that bloom from mid to late summer

A tansy spray can be made torepell cabbage worm as well as many other garden pests

http://www.wikihow.com/Make-Tansy-Spray