I have small black spots appearing on all types of plants: mint, oregano, lemon balm, cup flowers, daisies, bergamot, etc. The small black spots appear first and are very close together. Some of these stay as black spots, but others have the spots turning brown and the leaves dry and curl, then holes appear.

I've found some tiny insects that are black bodied with about three bright yellow stripes down their backs. Shaped similarly to a firefly, but less than half the size. But I don't know if these are creating the black spots, or if this is a coincidence.

I've taken the plant to the local gardening center and they can't identify what is causing this. Any ideas?