Lurking

Sitting in my office, looking out my window, I saw a Monarch butterfly flitting around the butterfly bush. I grabbed my camera and rushed outside to see if I could shoot some pictures, but by the time I got out there the butterfly had departed. Instead, I spotted this alien visitor lurking among the upper branches of the butterfly bush. He's the second, large praying mantis we've seen in our garden this summer (see my blip for August 8th to see a shot of the other one). Since they were both about the same size, about 4 inches long, I wondered if they might be the same insect, but the most recent one had a brown body, while the one I shot last month was entirely green. Does anyone know whether or not their body color changes as the season goes on?