This is stippling damage from a type of sucking insect. It could be mites, leaf hoppers, thrips and all are difficult to see or catch. Many flower species get this damage in the high heat and drought of the summer. It shouldn't overall affect the health of the plants though and doesn't warrant control. If your plants looks drought stressed you can supplement irrigation in times of drought but echinacea is pretty resilient and should be fine. 

Let us know if you have further questions. 

Emily