Can you use extension tubes with a macro lens?

I have a Nikon D3100 with a Sigma 50mm f/2.8 macro lens. I love taking pictures of insects, but to get close enough, my lens almost always scares them off. Is it a good idea to use extension tubes? If so, can anyone recommend some?

Of course, as long as the extension tube has the electrical contacts necessary to communicate with the cameras light meter.

Your problem will only be exacerbated using extension tubes. While they will allow you to get closer to your subject, they will NOT prevent you from "scaring off the insects"

What you need is a much longer lens, like a 105 mm macro. The longer the lens, the greater the working distance from the subject