This is a pair of blister beetles, Lytta magister. They can be abundant in very localized areas for a very short period of time. They are large and amusing, but be careful. When molested, these insects release a highly irritating chemical (cantharadin) from their body joints. This can raise terrible blisters on sensitive areas of the skin. Ingesting one is even worse: it can kill a horse that accidentally eats one with feed. As a rule, avoid touching brightly-colored insects:-)