Some of the Kashrus agencies have recently alerted regarding increased insect infestation in Red Cabbage.
It has recently been discovered that Red Cabbage can be infested with insects. As a result, the Star-K has upgraded its Red Cabbage inspection procedures from a simple thorough wash to the same procedure used for other leafy vegetables. Packaged Red Cabbage that is kosher certified as insect-free remains acceptable.
COR – Kashrus Council of Canada
Please be advised that we are consistently finding a high level of insect infestation in fresh red cabbage (purple cabbage). The small white insects can only be detected if the cabbage is opened on top of a light box. This is extremely tedious and impractical. Therefore, only pre-washed red cabbage that is certified by a reliable kashrus agency should be used.