What is this bug that is devouring my clematis?
This appears to be a margined blister beetle. Often this type of insect is a pest in field crops such as soybeans. It is less common to see them feeding on landscape plants, but if you have farms nearby, they may have happened over for an extra meal. They are pretty heavy feeders, and judging by the damage they do to soybeans, they may make short work of your clematis as well. I'd recommend treating with either liquid Sevin, or Sevin dust. You may have to repeat treat after 7-10 days depending on the weather and the severity of the infestation.