IDENTIFICATION — If you have columbine, you’ll eventually have to deal with leaf miners.
DAMAGE — They don’t kill the plants but they can make the foliage look rough. Leaf miners, the larvae of a small brown fly, tunnel their way through the leaves like the one in the photo.
CONTROL — You can get rid of these tiny pests with a systemic pesticide, but simply removing the affected leaves and throwing them in the trash is easier and cheaper.
For a really bad case, cut the whole plant back after it flowers. The plant will send up new growth in a couple of weeks. By the time this new growth emerges, the leaf miners will be gone and you can enjoy the clean foliage the rest of the year. Come spring, your columbine will once again burst onto the scene with colorful abandon.