I shoot a lot of insects from dragonflies to moths. My favorite setup is a Canon 5DMkIII or 7D with a 300mm f4 Canon lens, sometimes with an extension tube if I know I am only shooting bugs. The 5D is preferred for faster autufocus and better noise performance at higher ISO. But the 7D performs quite well and is a bit lighter. The 300mm focuses to 5 ft and closer with extension tubes. The focal length allows me to keep a good distance away so I don't disturb the subject, yet still get a close-up (dare I say macro?). I often shoot at f8 to get a bit more DOF. IS helps with hand held, but I will always use a tripod if I can. Occasionaly I can nail a flying dragonfly. I love the setup because with the 300mm I can do bugs and birds without a lens change. The attached photo was handheld with the 5D.

Black-tipped Darner. 5D,f8,ISO400