These are juvenile (nymph) Boxelder Bugs, a native insect that is more of a nuisance than a serious pest. They will not damage the plants and can be ignored. Use of an insecticide is not recommended, both because it would not be practical or work well for this insect, and because its use would potentially harm beneficial insects that you want visiting the garden to pollinate or control pests. The Boxelder Bugs will probably just wander off on their own later, though even if they continue to congregate, they shouldn't cause plant problems.

If you had kale struggle this year, the information in our leafy greens web pages might help diagnose the issue. If not, feel free to share photos of the plant's symptoms for feedback.

Miri